I believe they stopped it because of all the rainbows and browns in the rivers, so they don't all "just die anyway".
I remember when I was about 10 or so back in the '70s. My Dad had pick up us kids for his Sunday visit. On the way to his place, we passed by Pikes creek bridge on KR. There were about 40 cars parked along the road. We walked down to the river and it was crazy. 30 lb kings on every stringer as I remember it. We were watching for awhile and this dude with long hair and an army jacket says "Hey kid... you wanna fight one?" I said "Sure Mister!" He cast over across into a deep pool and handed me the rod. He said "count to 3 and give it a good rip with all your might." Three seconds later ZZZZZZZZZZZZZZZZZZZZZZZZZ the drag was screaming. I held on for life!! Finally got it to the bank. The dude's net was being used by somebody else at the time, so another dude was wading around throwing peoples hooked fish onto the bank for them, so he grabbed mine and threw it up the bank and down it rolled around a sapling. It made another run and we worked it back to shore and then he tossed it again on the bank and down it rolled around the same sapling. so with it double wrapped around a tree, it finally got off. Anyway, the fish got unhooked, but I was hooked. I love salmon fishing from the boat now. This year we had some screamers on that wen't going to be taken alive. Landed some 25+ fish but pretty sure the ones we couldn't land were big like back in the day.