I played without mods for quite some time, without having any really big problems. The first one I got was actually the one which shall not be named, for the one reason, that I wanted to play a family constellation, which required jealousy to be turned off (and I discovered, that the "no jealousy" LTR is borked).
After that I got overwatch and mastercontroler and it all went downhill from there. Or uphill? I now think, mods make my gaming experience much better, and without them, I would have quit the Sims a long time ago. Especially mastercontroler is sooo convinient! And a lot of tiny flaws in my game, I wasn´t even really aware of, have vanished.
Most of my mods are from Nraas, and a few from modthesims.
It´s certainly possible to play a smooth game without mods, but personally, I seriously don´t want to. Mods let my play the game I want to play.