There are many reasons why:
1. The first reason is that on dating apps like Tinder, you can't get the gist of someone's personality. Your opinion of the person is almost entirely based on how they look. Unfortunately, not everybody looks like a model and you end up being highly selective, because you know that you can choose someone who has more value lookswise. This can create a very false image of the person, because sometimes you can appear to be the ugliest guy on the planet lookswise, but your personality could be amazing because you don't have a conversation with that person. A lot of attraction is based on your looks, but it is also based on how you interact with the other person and your conversations in real life. Unfortunately, that's not possible through Tinder and people become disappointed in who they end up dating.
2. Secondly, most people on there are not looking for anything serious. Girls are most likely there for fun or validation. They're probably swiping through guys' profiles with their friends and laughing their a$$ off of the guys profiles. Or they just want a quick hookup and just sex and nothing else. The same applies for guys. Most guys on there are dbags who pose in front of a mirror with their six pack or perfect jawline thinking that they're an alpha male in the dating spectrum. In conclusion, you can meet a lot of very toxic people on Tinder. And if you think about it, if they're single, then most likely they have problems anyway and that's what made them single in the first place.
3. Finally, it's also about the imbalance in the dating market. The app is oversaturated with thirsty men who can't get any matches because they come off as desperate and sadly they never get noticed by women. Women receive hundreds and hundreds of likes from guys like that and they simply get annoyed and tired. I have seen a Tinder experiment where an average looking girl created a dating profile on Tinder with no make up or any of that BS and she got like 20 likes/matches in only a few minutes. The dating game on Tinder is automatically rigged against men because they portray themselves as having lower value.