That's just based on the ability to convince the management types though, and I'm sure you've heard of the phrase "nobody got fired for buying IBM."

For an executive, it's easier to justify outsourcing to a large consulting firm simply because of the security afforded by the choice and the ease of justification; rather than any technical abilities they may or may not possess, and certainly it does not imply its correctness.

The anecdotes you hear are from a engineering perspective, which is where the consulting firm has to walk the walk, exposing their true abilities. It is incorrect to dismiss that as being "salty" or "pretentious", and tint them with an angle of "discrimination". The lack of processes and guardrails in these consulting companies is an objective fact.