Indeed, different worlds. MMOs (and other online games, for example PoE and the like) have expected downtimes, usually on a weekly or monthly basis. It's just a fact of life. Very few games have the ability to do live hotfixes and patches for most issues - apparently Heroengine games in theory do, but there really aren't a lot of games using that engine in it's default state, and even those do go down for patches.
Online games aren't 24/7 servers, nor do they have any guarantee of uptime. I'm going to take a wild stab and guess that your MMO experience is limited to AO - trust me, the downtime in AO is significantly less than many other games with larger teams, larger budgets, and larger player bases. They could take down the servers bi-weekly for 6 hours and still have higher uptime than most.