First of all, it's simply ridiculous to demand high DPS performance from any job in DF content such as dungeons or hunts. As long as everyone is trying to actively contribute, it should be enough, even though their playing isn't optional.
However, when we talk about PF and raid finder content, the expectations are higher, since the content itself requires certain level of optimisation. In Ultimate, Savage and extremes, you should already be familiar with your job and know how to use it in a way that's the most beneficial to your party. Most of all you should aim for being as useful to your party as possible. If you know that you could tank the content (with an enrage!) in DPS stance and improve your party's DPS like that but you refuse to do it, making it harder for your group than it should be, it's understandable if your group doesn't want you with them.
Also, party finder groups are free to set their own entry requirements as they wish, no matter how ridiculous they are. And, at the same time, it doesn't make much sense for people to join a group where everyone else has a completely different mentality towards performance and optimisation. If you're excluded from a group because everyone else there is ranking significantly higher than you - especially for reasons such as refusing to play your job according to the current standard - chances are your mentality is quite different from theirs.
Lastly, there's nothing in the ToS against checking players' logs and including or excluding them from groups because of that. It's done all the time, even as written in party finder descriptions, and there is nothing that has been or will be done against it, since checking someone's logs doesn't even mean you're using a parser. All it means is you're browsing a website. That's like saying you're reporting people for saying they've checked your Lodestone profile.(Of course harassment based on someone's logs is and should be a reportable offense, but simply pointing out that your public records for a particular fight are too low for a group's requirements is not harassment.)