2014 was not bad because it was not an essential priority of any kind.
Way before Flash, most people had Windows and HTML comes with hyperlinks.
These go way back.
Decades ago, the Windows Media Video (.wmv) file extension was "associated" by default with Windows Media Player (WMP), the built-in Microsoft media player.
So you double-click on a WMV file, then it automatically opens WMP and plays your media according to the settings you have in WMP.
You could also associate other types of media files with WMP, so those type files would also launch the player. But WMP would only play the formats for which you have installed the proper codecs. WMV format file support was just naturally included for everybody with Windows.
OTOH you could install an additional media player like VLC and associate different file extensions with either player as you would like. So you weren't actually stuck with WMV that bad, if you had the codecs. And VLC had a lot of different codecs included, still does.
And still today, with something like Legacy WMP, new Microsoft MP, or VLC set to open when you double-click on one of your MP4 files for instance, there is naturally no browser needed. But if a link on a web page is single-clicked when it points to a similar MP4 which is posted on the internet, it will work too. Won't play in the browser of course without embedding and stuff, it'll just play the normal way, popping up in its separate media player window. Alternatively, you could just right-click and download the MP4 and play it later, this was common for those who did not have the bandwidth to smoothly play it as it streamed in, like on dial-up.
Flash arose as a low-performance alternative, intentionally compromising the animation or motion picture to use less bandwidth without being too ugly when played at the same rate the data comes in over dial-up.
With the <video> tag a media file will still only play if the correct codec is handling it as the data makes its way to your monitor & speakers. Different browsers and OS's will not behave identically, somewhat analogous to the regular old way, where end users had a variety of players and codecs all over the ball park which would not all do the exact same thing in response to a particular media hyperlink.