Isn't MPV is the only player fansubs are designed for anymore? Just like opening modern websites in Firefox/Opera Presto/Netsurf/etc renders things strangely when everything is designed for Chromium/Blink/Webkit, I would presume the same is true for video players.
>MPV/mplayer/other historic names is just the system GNU/Video library on Linux/Mac/Android/etc, used everywhere from your boot screen to the menus on your smart fridge, where all development has coalesced around
>the Aegisub devs all use it (on Arch BTW) rather than test in Windows 7 to play anime with Kawai Codec Pack in a VM or something, don't check the software outputs fully compatible files for MPC, Realplayer, Quicktime or anywhere else
>the preview Aegisub shows while the typesetter colormatches sign blanks and whatnot is windowless MPV
>the encoding previews the Vaprsynth/etc guys use is all MPV
>every person working on a release at any level is on MPV testing for MPV
>user instead opens it in an unmaintained WIndows XP CCCP, the subs are slightly lower than the fansubbers expected, or are timed slightly differently to introduce random bleed, maybe an encode sector join causes an unexpected crash at worst
>user complains in the nyaa comments
>"just use MPV lol. we don't even know how to make a CCCP targeted version wwwww"