I think I am showing my age when I say, I remember when Linux by default came with sendmail enabled by default. You could use your Linux box to send e-mail anywhere without it getting caught up in spam filters. Fun times.
Personally, I'd prefer to have to deal with the spam than to have to deal with the duopoly in email that we have today.
I think you misunderstood. If you fire up a mail server on your Linux box today and try using it for mail the big mail servers are sending your mail to spam due to a bunch of spam rules. These days, you need an organization with a known reputation for sending good e-mail to handle your e-mail so you don't end up in a spam folder. It's how the big players stay big.