Earlier quoted context omitted.
Limiting on testing is just taking away the unique Ferrari advantage. Previously they just took their design out on their private racetrack next to the lab. Now they have to test as all the others: virtually in computer simulations. And for a short time on the track. It's much more interesting to do the simulations virtually. Some even do the windtunnel testing now virtually. But only the richest.
So how do you explain that now after each regulation change and until the next, one team wins every constructor and driver title? Previously, dominance was never that total, not even during Schumacher/Ferrari era (and Schumacher was way better driver than Hamilton). But since 2010, no competing team is able to catch up.
But the stats disguise the fight; the fact that Mercedes have won didn't mean their position wasn't earned, frankly they've had a fair slice of luck in several races. For the last two or three years one could easily argue that Ferrari had the means to take them on and beat them, but their campaigns have unravelled for various reasons. Many races they've had to earn that win and many seasons where there was a fight throughout.
The fact that Maclaren has vanished into obscurity despite originally having a Merc engine, and RedBull and Ferrari getting in others faces so often has actually allowed Mercedes to keep their head down and get on with bringing home their maximum potential points haul per race.