Comment by zamadatix

The intent is only 32 bit apps get installed there, but there are a few problems in practice. Dunno why you're currently downvoted about it though.

The first is needing to know whether the app was 32 bit or not is sort of the main annoyance with that itself.

The second is not every app follows this rule correctly, for whatever reason.

The third is there isn't a clear path for mixed apps, e.g. Steam. On Windows, Steam is still a mix of 32 bit and 64 bit components, so there isn't really a "clean place for it to go. You could have one option of putting Steam in one or the other and then mixing 32/64 bit apps in that folder & you have the other option of duplicating things, moving the initial problem an extra directory level deeper. 3b is that Steam installs the games under its folder, and the games you can install can be 32 bit, 64 bit, or a mix - duplicating the problem yet again. Until the start of this year, Steam still supported 32 bit Windows and, therefore, you could also have 16 bit games be installed.

There were reasons to do the split in the early 2000s but holding on to each decision like this for decades after seems to cause more pain than it ends up avoiding.