Consistency and compatibility. No matter the OS, no matter the age of the used DAW
Technically, AIFF came first (Mac), but WAV (IBM PCs) became way more adapted.
FLAC -- free GUI encoding/decoding front-ends not available for all platforms
WavPack -- most used on Windows or only specialized DAWs, free GUI encoding/decoding front-ends not available for all platforms (MacOS for example only works as command line)
MonkeyAudio (.ape) -- only available for Windows
ProTools for example can't load FLAC natively at all (according to quick searches). Most DAW's still can't load FLAC files natively without converting to WAV first. Others took years on end to even support that format in the first place (like Steinberg Cubase/Nuendo, Apple Logic, or Presonus StudioOne). Then let us not forget,that there are also still users out there with old rigs and/or setups (older DAW versions), that can not access this format without strange means of decoding to WAV or AIFF first .
The focus should therefore be the common denominator: WAV
I understand that some users still experience storage issues. But you don't need to store your entries for forever (only ideally until about 30 days since the last game has passed). After that, you can delete the file and the posted link on the forum will just run into a dead end. No issues there.
I am working on possible solutions on that topic (including "non accessible links" each month) -- but this takes more testing on my end.