> wouldn't it be better for them to lower expectations?

There's two metrics here though which influence and confuse one another. Women get plenty of attention on the attractiveness side, but just because you can get laid doesn't mean you can get a relationship. It makes sense that if a lot of people are acting as suitors that you would then down select from this group. The problem is that on the woman's side you don't know if the suitor is looking for a relationship or just to get laid. Without a good metric for that, you can't properly down select and might just end up with a pool of only people that want to get laid. Especially if the primary initial selecting criteria is simply attractiveness (i.e. you're using an app). This is probably unsurprising considering in the digital world we often convince ourselves that we have stronger relationships because of tools like these (e.g. keeping up with friends more because Facebook) but in reality we don't because we are sacrificing the only meaningful tool to build and maintain relationships: physical time together.