> Your goal should be to use only sargable[1] operators, and eliminate any functions, in all your WHERE clauses and JOINs.

Or just use indexes properly; it's fairly common for modern databases to support indexes on functions of column values; using an indexed (deterministic) function in WHERE/JOIN criteria isn’t problematic. The Wikipedia article you link addresses valid concerns, but the specifics it suggests don't seem accurate for the features of modern RDBMSs.