If you’re not capable of setting up DMARC correctly then it’s a safe assumption you aren’t capable of adequately securing your email server. Which is even easie

If you’re not capable of setting up DMARC correctly then it’s a safe assumption you aren’t capable of adequately securing your email server. Which is even easier to mess up with much higher consequences. Even if you are not intending to be a spammer, if your server gets pwned you will become an unwitting one.