I completely disagree. For example understanding the theory gives me a very powerful bullshit detector because entire categories of problem which might sound merely difficult are in fact Undecidable.

Knowing that the actual regular expressions can be recognised by a finite automaton but PCRE and similar "LOL, just whatever neat string matching" extensions cannot means you can clearly draw the line and not accidentally make a product which promises arbitrary computation for $1 per million queries.

I agree that understanding something of how the CPU works is also useful, but it's no substitute for a grounding in theory. The CPU is after all obliged to only do things which are theoretically possible, so it's not even a real difference of kind.