Yeah, and that's exactly why I've never received spam through iMessage even once over many years (despite being active in a bunch of group chats and 1:1 conversations).

All while I receive whatsapp/telegram message spam on a fairly regular basis, despite not being active in any groups or channels on those apps (and in general, opening them maybe once or twice a week at most). The only reason I even use those 2 apps is to talk to select few old relatives of mine who are not very tech literate and who just happened to learn how to use those apps +a couple of friends who simply insist on using those apps.