I was confused on that too. It does have "?" for some of those things, not that they say what a question mark is, I read that as untested. Also, I'm not entirely sure what they mean for subtitles, but Plex supports burned in(to the video itself) subtitles, though you end up back in transcode land for that and it took alot of CPU power last time I tried [1]. Plus "instant browsing" is I guess accurate but a weird comparison point, Plex needs to scan files once and periodically scan for updates.
They may mean more specific things for all those things Plex "can't" do, but I can't tell from just the comparison page. Plex has plenty of issues, no need to make up more.
[1] A quote from their page on subtitles: Other formats such as VOBSUB, PGS, etc. may work on some Plex apps but not all. For the majority of apps, both VOBSUB and PGS subtitles will require the video to be transcoded to “burn in” the subtitles for streaming.
They may mean more specific things for all those things Plex "can't" do, but I can't tell from just the comparison page. Plex has plenty of issues, no need to make up more.
[1] A quote from their page on subtitles: Other formats such as VOBSUB, PGS, etc. may work on some Plex apps but not all. For the majority of apps, both VOBSUB and PGS subtitles will require the video to be transcoded to “burn in” the subtitles for streaming.