Sure, but not accessibility or UX design. There's more to a good UI than looking pleasant. Far more. I wish we hadn't unlearned that in the past decade, because Flutter and browser-based UI kits throw all of that out the window.
Discarding it out of hand by "qt is bloated" just feels disingenuous to me. You can add to that the fact that qml on the desktop if finally maturing into a viable alternative for widgets, and UI development with qml is such a breath of fresh air.
From a user perspective I remember that being a big thing some time ago when people didn't have anything already using Qt install did an “apt install” or “yum install” on something that did and saw the small tool they were wanting was going to drag half a desktop environment in with them as dependencies. The same could likely be said for GTK in reverse, I'm not sure what their relative sizes for similar features are these days.
Some use bloated to mean the memory footprint. IIRC GTK has more of a reputation for eating RAM than Qt, but again maybe people notice a single Qt app using a lot of resource (that would be shared if running multiple apps against the same libs) when it is the only one they run.
As you suggest, just stating that “<whatever> is bloated” without reference to some details of what is meant by that, sounds a bit like someone parroting old information and/or group-think rather than having looked into it recently.
Having said that the author has a minimal dependency stance in order to try to maintain a small footprint for the app (“I avoid unnecessary abstractions.” in the section about keeping things small) so any framework that isn't little more than a cosmetic wrapper could legitimately be called more bloated than using nothing at all and talking more directly to the standard OS libs. Also in context (discussing why the product is not cross-platform and is never likely to be) this is not the only reason being given and probably not the most significant one (there may be significant selection of cross-platform issues beyond the UI framework).
The key to a lot of what is in that document is the “It’s my project and I act like it” part. All too often we forget this very important side of things, especially with one-man or small-team projects, and people comment on project decisions as if using the product gives some automatic expectation that the creator will mould it around the needs/wants of a given user or someone's idea of “the community”. For an open source project the community has the option of forking the project or offering to fund the changes they want that aren't otherwise on the creator's roadmap (though obviously the larger the project, the less practical these options may be)…
That said, has there been any fundamentally groundbreaking crossplatform classic UI toolkits released since the 90s? (IMGui is the only one that has seemed interesting but that's specialized and not a general one really)
I'm pretty sure that something based on IMGui could be more or less isomorphous to React style rendering, it'd be up to someone to implement it though (and it'd probably be worth it since building applications at scale you win back a lot of time by not fiddling with state manually all over the place).
Using Chromium however is explicitly not where we should want to go (it's basically a kitchen sink in itself), but we go there anyhow (me included often) because it's just so much more quick thanks to progress in dev experience in the webdev area.
That's fair in the sense that I did not look closely at latest Gtk or Qt or WxWidgets.
That being said they certainly did not get lighter.
Last I checked Qt was over 10 MB of libraries). Sumatra is 12 MB and I'm guessing over 8 MB is fonts needed to render PDF documents.
So just Gtk or Qt code would be more than the whole app.
Latest Gtk4 does seem to look nice so maybe calling it ugly was uncalled for.
Edit: I just checked and Acrobat Reader requires 450/900/380 MB for Win32/Win64/Mac respectively [1]. One might argue that it does more than just read PDFs. But in many cases, reading PDFs is all that I need.
Seems like the author didn't look at cross-platform toolkits since 90s.