I looked up data from a calorie tracking app I used a while ago and I got just enough vitamin D. Main sources were fish, eggs and dairy products. However, I ate a lot and I'm quite sure in winter there will have been periods where I didn't get the recommend intake.

So if you live in a northern country and you don't like fish, I suppose it's quite a good idea to take a supplement.

Though as OP said, even if the sun isn't strong enough, there are plenty of benefits to going outside beside vitamin D.