No doubt.
I (generally) like taking myself offline. Thats how I learned everything I know (by fucking up). But thats also why I like to have my mail/monitoring outside my own selfhosted infrastructure. Cause those two things are something that should be running 100% of the time. And if I dont feel like fixing whatever I broke right this moment, I like to feel like I dont have to.
Sometimes I just go to bed whenever I broke something and fix it tomorrow. If I have to flick my light switches by hand until then, so be it, I can live with that. But mail and monitoring cant wait that long :P