That's true, but only initially. Once you get SPF/DKIM right, that you domain name grows a few years old (enough to be considered established) and that you nailed your configuration, there is no issue anymore. I've been running my own Postfix on a Pi in my home for about 5 years, and It Just Works ™. The only maintenance I do is updating the software (done when updating the rest of the OS), and I don't get shadowbanned mails anymore, even when sending to outlook.com (which is. by far, the worst peer when self-hosting emails).

EDIT : by the way, fun fact : it seems not as related to IP reputation as it's often said (well, unless the IP has bad reputation, of course). I changed my ISP late last year (thus changed my IP), I was very afraid I would lose my good reputation and have to start over with getting my mails shadowbanned, and… nothing happened. My mails just got delivered as usual. So I bet the domain name is at least as important as the IP.