That's fair -- one simple answer is privacy: each service you sign up for gets its own email address, but they're all tied to your 1trial account behind the scenes (if you choose to create one - it's optional), so you can still keep track of it.

I bet that the second email address you have can easily be tied to your identity. Same reason Apple Private Relay is useful.

Before I see value in a product, I may not want to give them my actual email address because I may just end up using it once.

I suppose it could be abused, but that's certainly not the intent.