LFR is raiding in terms of size but not organization. LFR takes the challenge and thinking out of raiding which makes it more attractive to players that didnt like either the challenge or maybe just couldnt thought process as fast as others in their raid group.
Gonna use my BC-Wotlk guild as an example. We were a 25 man guild. We had a small 10 man group that expanded to 25 by the very end of BC enough to kill Magg and Grull with almost a full guild group. Now i didnt know this then but my guild sucked. It was terrible. We had maybe 3 solid players at that time. On into Wotlk some of our players got better but alot were the stand in fire type, or come to the raid drunk or high type, or the play like your a 70 year old with arthritis type which we had in ulduar.
Back when we did 25's i know about 7 of us that really loved raiding. We loved the challenge, we liked the planning, we liked the culture. Of those 7 i only know one that is still raiding like that today. Others are pvpers, some quit like me, and others have picked up LFR. All the others in that guild are LFR raiders today. They dont run "normals" of the current tier. They run old raids and run LFR. When DS was out they ran firelands. When firelands was out they ran BoT etc.
This is where the "raiders" went. All the filler spots in 25 man guilds are choosing not to get called out every night, choosing not to stay up late, choosing not to feel like a dumbass because they cant recognize that their character is standing in a void zone, and are choosing to do LFR. This is my experience from an old guild and even the guys i hang out on vent with. They couldnt even kill 1 boss in the first MoP tier. I know that 2 of those guys were good raiders but they were playing with players that were Filler. 2 goods and 8 bads with zero leadership quickly stopped them from trying to raid. And guess what they did everyweek? LFR, LFR, LFR.
LFR is giving bad players an out and good players dont have enough bads to fill up spots.