Tmoose - the issue is that the code is not entirely clear on a) how many you can have or b) how to correct the problem if it's violated. The IRC calls for a maximum size of joist depth/3 and a minimum of 2" between holes and between holes and edges. That's it. You can drill a series of holes 3" in diameter with 2" clear between them for the entire length of a 2x10 joist and still technically meet code. I wouldn't want to stand below or on it, though.
I dug into this a while back. From what I can tell, those guidelines are 100% empirical. I found identical notching and boring guidance in publications back to the early 20s with no evidence of engineering analysis or testing. Just a 'this is what we do, and it works.' Unfortunately, that depends on people not drilling 10 holes in a row. After all, houses in the 20s didn't have 30 electrical circuits, a web of Pex piping, hard wired internet infrastructure, AV cabling, etc. all running over top of the living room.
There's plenty of literature out there for reinforcing Engineered wood products - the manufactures have a vested interest in making sure their product isn't the reason for a headache. But commodity lumber? There isn't really a push for that, especially as its use for floor framing falls further and further out of use. So there's not much out there for a good, US code compliant fix.
