This pretty much breaks the entire usecase, as you cannot build an IP reputation.
To the other point, if you have a problem with spam scores, you are probably sending too much mail for this sort of solution (consider Mailgun 10,000 emails/month for free). For an individual it is fine, not for use as a mailing list. A clean IP address (every IP I've ever tried was clean), DKIM, and SPF will allow you to hit pretty much anybody. It might take a few people pulling you out of spam on gmail before you can send to them, but I think that's true of any new mailserver.
I typically don't send more than 40 emails a day. But have several domains I would like to have email for... paying $10/address is a bit steep to say the least for that use case.
You are paying for convenience here.
I can't say email limits are ever something I've thought about.