@boo_ @AAKL @9to5Mac Hi Klara. I reckon you've made fine points & well expressed. I shall readily & entirely concede that my choice of comparison was crude & legitimately liable for criticism. Let me try though to explain what was/is in my mind, wrt all the Mozilla shenanigans & imbroglio.

First, i readily join the bands of voices criticising Mozilla over many years for apparently letting Firefox fall far behind the competition. One does not even need to consider the chromium-based competition, to be able to criticise their apparent loss of interest in FF until comparatively recent months. Even staying within the Gecko-sphere, the fact that single-Dev projects like #Floorp & #Zen have been able to create quite excellent forks in short time that far exceed the limited innovation Mozilla have done in FF for many years, should shame them. Moreover, other single-Dev projects like the fabulous #FirefoxSecondSidebar, & then also ofc the AOs #TreeStyleTab & #Sidebery, illustrate by comparison how negligent the FF Devs have been [or maybe, been allowed to be], in not natively incorporating such great innovations that elevate the UX so considerably.

Secondly, the brouhaha recently re the ToS / ToC or whatever we call it. Mozilla possibly could not have been more ham-fisted & incompetent wrt how badly they mismanaged the situation, & they deserved a lot [but far from all, IMO] of the worldwide criticism they incurred. As to the germane details themselves, fwiw i tend atm to fall on the side of the argument that they were very clumsy, but not being evil by design... & in matters like these i always ask myself the counterfactual "well ok, do i now distrust them enough to actually abandon them & thence choose to cut off my nose to spite my face by entering the actual proven evil empire of chromium-based browsers?". My answer remains NO!!!

Thirdly, the #AI problem. Lemme state upfront that i despise the entire global fetish that's erupted for #LLMs / #GenerativeAI. I loathe & despise the vast intellectual property theft perpetrated in training these things, despair at the shocking environmental implications of them, & alternatively scream & cackle at the gross human stupidity manifested by peeps all over the rock blindly accepting the hallucinated garbage produced by these monstrosities. Do i want AI in my Foxes? Nope. Would i prefer Mozilla was not apparently bent on this path? Yep. However, again i ask myself that counterfactual, which i am able to mediate with the knowledge that atm anyway, knowledgeable users are still able to actively choose not to use it, & deactivate it, in their Foxes. Is that the best way Mozilla could have done it? No, ofc not. Is it overall a scenario that i can still use to my advantage? Yes. Is it a least-worst alternative to the chromium horrors? Yep.

A Third-&-a-Half point arises. I said above "knowledgeable users are still able to actively choose not to use it". What then though for non-knowledgeable users, for the non-geeks, the "regular peeps"? Here i admit my attitude is harsh & possibly mean, & i shall accept all criticism of it. IMO the "regular peeps" do not care one jot about any of this. They often struggle to grasp that a Search Engine is not a Browser. Many do not know or care that they have a substantial browser choice, beyond whatever came on their device. They think of "Browser" & "Chrome" as being synonymous & indivisible. They have no idea that they do not in fact have to tolerate their present miserable web UX of sites drowning in ads, trackers & malware. They have no idea of the existence, much less purpose, of #uBlockOrigin. I posit that these peeps are the target market, aka shooting fish in a barrel, of the present AI fetish, who know not &/or care not about any & all the ills of AI, who are unmotivated to lift a finger to improve their online UX, & who simply desire to accept whatever slop is served to them. IMO none of the recent Mozilla noise is relevant to them, as they're either not using FF anyway, or if they are, do not care about anything behind the curtain.

So, my OP was primitive & arguably invalidly comparing apples with oranges, but i wrote it with all the above in my mind. Fwiw.

Okay. As one of my attempts to make a viral post, let me make a poll:

Since you're probably on desktop, and using a browser to read this post, may I ask you: do you use vertical tabs or prefer horizontal ones?

@bernd @al3x I used #TreeStyleTab for years, & loved it. But later, when its Dev began jettisoning core functionality for he, & others, to then pick up in companion #AddOns, i became jaundiced... instead of needing just the one AO i then had to have about 8, & i resented this a lot. Also, i became disenchanted with the Dev's staunch refusal to countenance many user requests that would have helped broaden its functionality. Later, i discovered #Sidebery, & as i slowly explored it, & learned how to finesse its wonderful [albeit, sometimes confusing] granular settings, i realised that not only does it have all of TST's original core functionality altogether in the one AO, it also has various features & functions not in TST, such that overall, ***for me***, Sidebery is a far better AO than TST.

That said, i can only strongly agree with your sentiment behind your

>just that word "once", basically saying that the vast vast majority of #firefox users will never experience this

As a geek, who loves details & options, all this stuff is seductive & fabbo, but it should all be available with less friction to a wider array of users as well. Otoh, i suspect it's likely true that even if the friction was removed [somehow], a very large mass of users would still ignore it, simply coz this kind of thing just does not float their boat.