I only suggest that if there aren't enough healers, or the event (and dungeon) requirements change, or the game itself adds a system-created healer to the game. I don't have the statistics, but it would be necessary to compare the number of games that are made of dungeons and skirmishes.
Today I held the event, after 15 minutes of waiting. I saw a lot of DPS typing +event. I also saw messages for Madam Eva: Time is precious, Madam Eva, and also, Madam Eva is very busy. Of course I went to do other tasks in the Dread Ring. And after doing the event, I did NOT do Inception. And why would you? To win a gem?…
Well, I tried it, but doing it alone is not an option. That's too many enemies for just one character. If the system adjusted the number of enemies to the number of participants, it would be possible.
Well, it can be done with fewer participants. I did not know, I did not know it. One question: Is the level and number of enemies adjusted by the number and level of participants?
I think it's hard for the system to build a group of players, because most of them are DPS, there are fewer tanks, and very few healers. The event calls for parties of 3 dps, a tank, and a healer. The role of healer, in this event is not so important. Maybe you could change the requirements so that groups can include 4 dps…