$628.000 is not exactly shoestring budget.

Maybe not as much as others are using but I would say by far the most university research groups couldn't afford that.

I cannot tell if this is sarcasm or not.

Anyways, from what I read it seems to be fine as well. But it is certainly not better just because it is from a "private company".

All the spammers need to do is use your @my-name.addy.io to check where else you've signed up (through hacked data sets) or send more spam. And arent the emails you can forward to very limited (1 I think?). That just beats the purpose of aliases.

True that could happen. However you can use a shared domain to avoid this. It is one more click to generate a new mail address if you think it is worth eliminating that risk.
I don't know where you get the 1 reply limit from. Can't find that on their website and definitely wrong for subscribers.

Hmm after reading through the post, are you posting this because you just learned about it or this is their marketing speaking?

Definitely not affiliated with them in any way. Just a happy customer and though others might be profiting as well.

So just use a cheap custom domain with wildcard email forwarding or services that have conditional forwarding instead of adding 1 more layer that could fail you

Sure you could do that. But I am sure that 99.9% of people that use gmail can't and won't.