Something called the internet happened. There's a certification process on consoles that takes time. This way games can release sooner (with a day one patch) and developers can keep working on the game instead of sitting on their hands.
I get why it bothers some people, those with bad internet the most, but the solution is to have devs not do anything from cert to release date and delay every game. Day one patches solve that.
I'm not saying is a good thing per se but I don't find it that bad but, as I said, I'm speaking from a place of privilege and I can understand some people have crappy internet connections.
The internet happened long before this, and nobody says devs need to just 'sit on their hands' between going gold and the release date. Again, this is stuff that absolutely could have happened last gen and didn't (partly due to the policies of MS on patch sizes). It's not like they're working on DLC or just small bug fixes, day one patches are HUGE now. 10+ gigs is lots of shit like art and audio or video assets, the kind of shit that, regardless of anything else, should absolutely be the same as what is on the disc unless the disc version of the game is flat out incomplete.
It's not something thjat would've happened overnight if it weren't implicitly allowed/encouraged, it's a way to cut budgets indirectly, shipping your game a month sooner is directly benefitting publishers at the cost of the consumer. Like, literally the day this gen started is when this practice began, there's no reason that we should think something magically changed between 360/ps3 and One/PS4 other than them being allowed to get away with it.