Also foreign keys are a mixed bag. See https://stackoverflow.com/a/83393/585411 for some of the pluses and minuses. I've seen very experienced people in significant projects go both was on the value of foreign keys. And a lot of the complications are more of a barrier for people who are just learning.
I've personally been on both sides of this fence.
For the record, I first encountered arguments against foreign keys around 20 years ago from a VERY experienced Oracle DBA. He knew what he was talking about, and had actually written some of the courses that Oracle used to certify DBAs. He pointed out that our transactional database for our high volume website was already pushing the limits of what our hardware could do. Maintaining unnecessary indexes or integrity constraints was going to take our database down.
Since then I've kept track. And found that the benefits versus downsides are more finely balanced than I would have guessed.