I can agree with your point of view where it concerns your own database usage, which I cannot see as typical of relational databases in general. Rebulding all data every day surely is not the norm as many databases are simple too big to even try anything like that or need to be accessible 24/7.

The only situation where I can personally see foreign keys as not/less needed is in a staging database to feed a dimensional data warehouse. Anyway, an index is not a replacement for a foreign key, nor is the other way around.