To be honest it’s mostly FUD. Self host email is perfectly doable provided that:

• you don’t use your home IP
• you do DNS records correctly
• you do DKIM & DMARC correctly
• you don’t send spam

What happened to me over the years was having the subnet my ip was is being associated to spammers, and that was a problem. It took several iterations with blacklists and my provider to get it sorted. That’s why I recommend using a reputable service provider that take care of spammers in a timely manner.