For example the Nikon Z 50mm f1.2 is 1090 grams, 150mm long, and has a 82mm filter size. The Canon RF 50mm f1.2 is 108mm long, but the other dimensions are similar.
Compare that to a Leica Noctilux 50mm f1.2 with a Techart, Megadap or similar adapter (available for Z and E mounts) for autofocus abilities: 405g lens +150g adapter = 655 grams, 52mm lens + ~11mm adapter = 63mm long and 49mm filter size. A little more than half the numbers in all dimensions.
This link approximately shows the size differece (the M to L mount is indeed smaller than the M to Z or M to E autofocus adapters, but the difference is small)
All of these have the same focal length (50mm), max aperture (1.2), and autofocus. So why do these newer mirrorless lens designs have to be so much bigger and heavier than using an old manual lens with an autofocus adapter? Sure the autofocus speed may not be as fast with an adapter but why can’t they design a native autofocus large aperture lens that is tiny like the Leica M lenses. Clearly it is possible to do so.
The overall effect of patents is difficult to assess but there’s arguments in both directions.
Patents mean that small niche companies can bring items onto the market safe in the knowledge that larger players won’t just copy them and drive them out of the market
The same goes to companies which just make copycat products (see Amazon today if you want to know what such a world looks like) in countries with cheap manufacturing and labor costs.
Patents mean others are incentived to become creative themselves, thus adding to the total level of innovation present in a market
Don’t forget that patents only last for 20y max, and you can license patents too.