Why doesn't Lemmy/Piedfed use ALT tags as much as Mastodon?

I am frequently on Piefed (Lemmy) and occasionally on Mastodon and I noticed they use ALT tags for images way more on Mastodon than we do here.

Anyone know why this is? it is more about the software or the culture or maybe just historical?

It seems like a good idea to always set the ALT tag for an image post on both services, and I've seen many ppl on the other site say they won't boost (share) any image posts without ALT tags (since vision-impaired people really benefit from them).

Just curious...