You raise very good points, that together make the picture even more complex :).

> The company developing Slack has probably done the net work of building it 20 times over as its feature set developed and morphed over the years

That's definitely true, especially in areas where they were innovating (or at least experimenting with features that were not common in the space). There's a cost to R&D, and I'll agree that preferring velocity is important to minimize that cost, which justifies the use of "nice for devs, bad for UX" tools[0].

> I'm sure Slack's actual complete feature set eclipses Ripcords

That's true. Ripcord doesn't replicate Slack 1:1, there were few "sparkly" that were cut (at least when I used it ~2 years ago), and of course a lot of the chrome that got removed could be considered features by some. But at least by metric of productivity, Ripcord's UX eclipses that of Slack.

> (most of the difference coming in via features not essential to most individual users, but key to the business)

In this particular case, I'd say it was 90% just removal of resource-intensive bloat. But that's a good observation in general: one of the reasons some users are dissatisfied with official apps is because of what they[2] deem as user-hostile features, existing to exploit the user instead of aiding them. Obviously, they're put there because they're the key to the business. Plenty of obviously bad UX can be easily explained when one looks at how the vendor actually makes money.

> How many web page previews, videos, images, etc. are in those tabs?

Ripcord either doesn't load those or is lazy about it. But when it does, you at least get the full picture, instead of having to click through some gallery-like popup interface :).

> apps built with [Electron] can be fast (e.g. VSCode, Github desktop client, Discord)

People will contest with you here because they're using a different reference point for "fast". VSCode is impressively fast... for an Electron app. Not so much in comparison to desktop-native apps implementing equivalent features. And that's the one well-known exception, a typical Electron application is noticeably slower and more resource-intensive than an equivalent desktop app.

> large constant factor for install size (~50mb base)

This is not something that people care about unless you're doing something silly, like an Electron TODO app that weighs 50MB and uses many times more of RAM, where the reference comparison is against a WinAPI app that would weigh 50 kilobytes and use not much more of memory.

This is also why people don't generally complain about VS Code being Electron - it actually makes good use of all the features its platform offers. But most Electron apps? Picking Electron saves developers a little bit of time, at the cost of heavy resource tax for all users. That's annoying. Especially if you have experience with native software that gives you reference points to compare.

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[0] - I'm definitely guilty of this myself. At my previous job, I developed a prototype for 2.0 version of the company's flagship product in two weeks, in... ObservableHQ[1]. The actual work to reimplement those features in our product took almost a year. I did joke we should probably ship the prototype in the meantime (especially given that our main competitor was an Excel plugin), but we never seriously considered that.

[1] - https://observablehq.com/

[2] - And when I say "they", I also mean myself in most such discussions.