As far as Canon...yes, they are SLOW. But as others have said already, Canon does do a lot more testing, they make sure what they develop actually works. Nikon and others are quicker to market. But they take risks. The D750 is on it's second recall notice.
In the end, you get technology that might not be cutting edge - but it just plain works. Canon builds machines for pro photographers and enthusiasts. They don't put out gear as quickly as they can to win on 'specs' for the tech junkies that only care about tech - not photography.
The proof of that is simply observing the popularity level (volume of discussion, praise, recommendations) of the brands amongst the TECH world. By tech world, I'm talking the guys who review computer gear mostly and electronics secondly. Sony and Nikon probably have by my estimates, a 10:1 advantage here or more. I rarely see a technology blogger or vlogger talk much about or ever recommend a Canon. It is almost always Sony or Nikon. Why are these guys even relevant? Because they outnumber camera and photography related review sites, and they are more dominant across the web.
Ok, but why then is Sony/Nikon more popular? Because on paper and on geeky tech specs, the Sony/Nikon looks better than the Canon. They don't take any account for the final image results, selection of lenses by those who know what they're doing, how it works as a system as a whole, ergonomics and controls for working pros having to hold the thing for hours, etcetera, etcetera.