I've seen many people complain about it, but never had a problem myself. I'm wondering if they are actually spamming gmail users, or maybe if gmail and similar

I've seen many people complain about it, but never had a problem myself. I'm wondering if they are actually spamming gmail users, or maybe if gmail and similar large providers are biased against new domain registrations, and people starting new mail servers often have new domains. Or maybe they don't do the basics like working DKIM, SPF, TLS, etc and they get penalized for it.