I self-host email, never needed G Suite

i have been using mailinabox on a cheap vps and beyond outlook, no other email provider has had trouble communicating with me.

i would say "i do not understand why anyone would want to use mailgun et al" because my email server needs an update once a while and it just chugs along fine. i do not run newsletters and subscriptions, just transactional office email so why isn't that more popular/more accessible? and, more adopted widely?