> Upstream is just giving them software for free on an as-is basis.

While the "we're entitled to bugfixes" attitude is definitely annoying for software maintainers to deal with, and you (as the end user) aren't entitled to anything from 99% of open-source projects... this is Chromium we're talking about. The browser engine that powers 75-95% of all Web browsing (it's very hard to pin down actual numbers, but it's huge). It is not too much to ask that the Chromium maintainers either 1) test all the combinations of optional flags they have, or 2) declare that some of those optional flags are no longer optional. In other words, to act like professionals.

(I don't use Chromium myself — switched to Firefox years ago because I tend to open a lot of tabs, which make Chromium seem to just gobble up RAM, and Firefox appears a little better at RAM management, or at least it did at the time I switched (haven't checked recently). So this isn't "the Chromium team owes me something", this is shaking my head in disappointment at what the Gentoo maintainers report that Chromium team is doing, or rather not doing. As I said, there are some projects — the Linux kernel is one, and Chromium is another — that are so widely used that a certain level of professionalism should be expected of their maintainers. I agree that that attitude of entitlement is not deserved in about 99% of open-source projects. But Chromium is part of the 1% exception, IMHO).

(I too use Firefox, even on Android.)

I just don't like this idea that downstream maintainers need to be saved from themselves by limiting the options upstream provides them.

Downstream are not end users, which I agree should only get tested builds. They're professionals too, and they can be trusted to pick the configurations they want to build, evaluate how much more testing they need, and cut out configurations from their support matrix if they don't have the resources to support them.

Also, this idea that a professional project wouldn't offer untested combinations of settings to other professionals is why people follow up asking about Linux. A quick search tells me it's got ~19,000 Kconfig options[1].

[1]: https://dl.acm.org/doi/fullHtml/10.1145/3646548.3676548