That argument doesn't really hold water when applied to aircraft manufacturing.

Commercial jets are not indistinguishable commodities, there is a ton of variation in design and mission ideologies (control systems, materials, hub-and-spoke vs point-to-point, etc.)

The type of goods and barriers to entry are more similar to e.g. car manufacturing than to utilities like ISPs.

If Boeing and Airbus weren't artificially inflating administrative barriers to entry we'd definitely have more competition, and consumers would benefit, not suffer.