The opportunity cost on the front side is often worth it but the long term benefit on the back side is you aren't dependent on that SaaS, are running stuff you know something about and have a lot of flexibility.

I'm from the old school, I use SaaS/PaaS mostly for stuff I know is painful to do yourself (sometimes file storage, nearly always email) but the rest lives on vanilla boxes configured with ansible (frankly ansible is faster to use once you get your head around it than learning 5 different PaaS setups).