depends by what you mean by "people". If you mean like just regular people than could be that they don't find it fun or just don't like being bad at things. If you mean by people in the VSRG community then oh boy what a can of worms to open.
1. Combo Scaling Score - Score is based on your combo. If you want to get a really high score you'll need to full combo. This is far right? Well let's say you're trying to beat your pb. You have a 925k with an accuracy of 98%. Well let's say you get a 98.50% run but you missed a few times so oops! Now you have a 910k score because of those misses. You can tell where I'm getting at here.
2. Rates - The only rates that are free is DT. Any other rates you have to create your own, ask someone, or use a program. Other VSRG games such as etterna and quaver let you change the rate within the game. While lazer does fix this issue it's still dumb that we can only play DT for stuff.
3. SR - SR or star rating is extremely stupid. As pointed above, sr is more based off of nps instead of density and complexity. Tech maps are severely underrated and it's easy to make farm patterns.
4. Mods - A while ago mods were ranked and gave multipliers. Hidden, fade-in, and even flashlight used to give a mutlipliar. This was unfair because some people play with these mods active even without the extra boost. Same with hr. although I don't remember the entire story of hr. So that's why mods don't give extra pp besides DT/NC
there's probably more but I'm just going off the top of my head