prozacchiwawa on Nostr: It looks to me like the reason they're doing that is to minimize the amount of actual ...

It looks to me like the reason they're doing that is to minimize the amount of actual transferred data when doing expose. The paint each pixel's 16x16 rectangle individually rather than the whole bitmap. In days gone by, this was over a socket (and still is even if a local socket if you use XPutImage instead of xshm).