I think the merchant of record bit is a bit overblown for a lot of side projects.

Tuvalu isn't going to extradite you for not paying them their $5 VAT.

If you're frequently dealing with multiple jurisdictions (especially with EU) and the fees don't add up to 10% or higher (which MoRs can do if you're in a less popular jurisdiction), it can make sense to take care of admin headaches.

That might be many projects, but it's certainly not all. I've written about this from the "third world" perspective over here: https://nik.software/building-global-wealth-from-south-afric... (and the "Accepting Payments" section above it)