"everyone has rights to use it in terms of condition" - Does the terms and conditions even cover usage of individual pieces of content? Is there a section on crystal tower? A section on companions? Last I checked ToC only included basic rights and regulations for overall use of the software.
"square knew this created party finder for all the little elitist to create their own party rules and social outcast system" - Assumption blatantly colored by elitist hatred. This was a tool they added to assist players. Any elitist context is yours alone, and you couldn't possibly assume it's there intention to please "the little elitist." Especially with the negative tone you wrote that with.
" I would love for you to tell me where does it say that everyone has to know the fights before attempting." It doesn't say you need to know the fights before attempting, but can we please use a little common sense and context? A Sastasha run is the first dungeon in the game. A dungeon clearly designed for training and practice. Obvious people will enter such dungeons with no prior knowledge and that is perfectly ok. However, Titan Ex, is NOT a fight intended for training. It is intended to be high level content for people who've already mastered Titan Normal Mode. To suggest that it is the same as running Sastasha for the first time is to blatantly ignore the clear and obvious differences between those two pieces of content.
This brings me to my point. There are two sides to this discussion. The "don't enter DF until you've seen a video or did some research" group and the "I want to join without knowing anything at all" group. Guess what guys. You're all wrong. This issue is not clear cut and dry like that and there are a ton of gray areas. Just as I pointed out the differences between Sastasha and Titan Ex above. Any discerning individual can tell that those two fights are for distinctly different people and require a distinctly different level of effort in order to tackle them. In Titan it makes more sense to prewatch a video, but in Sastasha there is no point to that exercise. The context of the dungeon and the level of difficulty it presents should be more heavily considered than some black and white answer here.
TLDR: You're all completely wrong. DUTY FINDER SOLELY EXISTS TO FIND A PARTY TO RUN CONTENT WITH. ANY AND ALL EXPECTATIONS PAST THAT ARE YOURS AND YOURS ALONE.