Why do most people plateau after a few months of training? Genuinely curious

I've been training for a few years now. Nothing crazy, just consistent gym work focused on getting stronger and building muscle.

At some point I noticed something that bothered me. Every program I tried - free ones, paid ones, ones recommended by people I respect - worked for a while and then stopped working. Not because I stopped trying. Because the program wasn't built for me.

My schedule changed. My recovery was different from week to week. The exercises that were supposed to work my chest were actually destroying my shoulders. Nobody accounted for any of that.

I started asking around and realized almost everyone has the same experience. The first few months go well because any program works when you're a beginner. Then your body adapts and you need something more specific. At that point you either pay for a real coach or you're on your own guessing.

Most people guess. Most people plateau. Most people eventually quit.

I'm not an expert. I'm not a coach. I'm just someone who got frustrated with this and started thinking about whether there's a better way.

Curious if others have felt the same thing. What actually moved the needle for you when you hit a wall? Was it programming, nutrition, recovery, something else?