The decision to not supply H.264 is ideological for sure, and I can understand that from the patent perspective, but then they have MP3 (patent-expired in 2017) but not MPEG-2/H.262 (patent-expired in 2018).
Also note that VP8/VP9 is still patented, but just licensed freely. IMHO that's less free than patent-expired (public domain).
My understanding was H264 is kind is licensed freely too after Cisco made their agreement usable for everyone ?
Firefox can support mp4 over h264 despite their clear FOSS aligned goals , I am surprised that Wikipedia whose goals more align to open information rather than open source directly has challenges .
e.g. there was a pretty strong consensus about not supporting MP4 back when the WMF asked whether it should be allowed, mostly on "it's not free" grounds: https://commons.wikimedia.org/wiki/Commons:Requests_for_comm...