There's very little reason _not_ to prefer wheels in general; we might not always be able to use them (e.g., we may be on a platform where wheels are rarely provided, or even where packaging doesn't currently have any concept of the platform such as iOS), but we should use them when possible. AIUI, we rely on some things (in tests?) which aren't in the Buildbot wheel (c.f. https://github.com/buildbot/buildbot/commit/2d351c2270a22302149eecd11265ea2ce3ec6617, https://github.com/buildbot/buildbot/commit/d34e1ccd3e62748b6d0c83965486774cdfb1dacc, https://github.com/buildbot/buildbot/commit/7d5c1b1ccb7ff2fc01b44b064851cea8fc7af74c), but maybe the 2021 change (shipped in 3.5.0) gives us enough of what we care about in the wheel? It sounds like prior to that they didn't really consider the testing API to be public, which meant there was little-to-no way to test Buildbot configurations.
<rdar://problem/116915892>
(I have a change locally for this, but need to step out for a bit; will upload PR once I'm back.)
Pull request: https://github.com/WebKit/WebKit/pull/19045
Committed 269817@main (dba0adf16439): <https://commits.webkit.org/269817@main> Reviewed commits have been landed. Closing PR #19045 and removing active labels.
Re-opening for pull request https://github.com/WebKit/WebKit/pull/19835
Committed 270059@main (219eb0bb7b43): <https://commits.webkit.org/270059@main> Reviewed commits have been landed. Closing PR #19835 and removing active labels.