This is exactly what "elitism" is by the way. Show proof of doing the thing or get kicked. Casual? Get the fudge out of here!
Only a problem if all the new, better equipment is shoved there, which is the norm. If all the new, better equipment is not shoved there, nobody will play it. Sure, the "hardcore" players say they enjoy challenge, but that is only if they get rewarded for it. This has been proven time and again.
This is not what Expert Matching does on the Japanese version simply because the requirements are not that difficult. The requirements essentially check to see if the player has demonstrated being capable of handling content at a decent speed and are capable defeating particular enemies and upon doing so allows them to participate with players who have also completed these tasks.
I have played with several "casual" players who have met these requirements and it simply is a quality-of-life filter that separates you from the players who will throw an Emergency Quest just because they refuse to learn the game. You see significantly less turret-Bow Bravers who spam Million Storm as their only attack, significantly less Heroes who "fly to win" holding Rising Slash from enemy to enemy, and much stronger team synergy in general than compared to a non-expert matching session. If you have seen any of the Emergency Quest Buster Quests we have had on our end (Hostility and Madness, for example) you would have seen how high the failure rate is on Super Hard or how the Mining Defense tends to have rough patches of difficulty due to the team not fully pulling their weight.
I really do not believe we should have had to need something to filter out players who want to do well and players who just want to play around but there is quite a bit of content coming up in the future where the performance and overall score the entire session gets will determine their rank and rewards. The final Emergency Quest raid also disables returning to the Gateship upon dying so if you die and don't have any Scapedolls or your allies are out of Moon Atomizers you are forced to abort the fight.
This doesn't stop players who aren't in expert matching from playing the game and enjoying the content, but rather it does end up becoming noticeably more difficult when all of the capable of players are no longer largely carrying teams that rely on them. From my point of view-, this should hopefully encourage players to get better at their classes and gameplay if they wanted to succeed because this game has very few failure states (even those Emergency Quest Buster Quests still give rewards for failure).