Do I need an alias email service?

cross-posted from: https://lemmy.dbzer0.com/post/70471346

I started looking into email alias services like SimpleLogin, Addy, etc. and I'm wondering if I really need it. Here's why:

My email provider has domain alias functionality. I can connect multiple domains to it. Let's say I'm [email protected].

I can buy domain2.com and create an email address called [email protected]. All emails (to both addresses) will land in the same inbox.

I can also create a catch-all email address so that I can create login unique emails for each service, like: [email protected], [email protected], etc.

So I guess my question is: What do I get from an email alias service that I'm not already getting from my email provider?

Is it maybe that I won't be able to reply from the service emails? Like, would I not be able to reply from [email protected] since it's only a catch-all? So I can receive mail to it, but can't send from it?