There are many sources of competitive advantage, which includes but is not limited to good hiring practices and the development and retention of talent.

Companies which were not dependent on cheap/competitive talents were able to get away with many inefficient work practices. Companies which are not dependent can and will still do that. Introspection is stressful and costly, change even more so.

"This is why great designers, salesmen or computer programmers are still highly valued": A very narrow selection of professions where productivity is very sensitive to variations in ability.