Yes, basically that. I set up mail servers for a company in 2001-2008 and then it was way easier. I tried to do it again five years ago, for my personal server and quickly found the landscape changed a lot. But it is doable.

Fair dos. I do run my own mailserver and although I have had problems I haven't found it impossible. The complexity in running a mailserver has for sure increased since 2008 but it hasn't seen the same level of complexity expansion that, for example, making a web site has.

I do use SPF but I don't use DKIM or DMARC. On the inbound side, I do use greylisting and anti-spam. I don't tend to change my config between releases of debian stable.