If dark matter, which makes up 80% or more of the mass, is smoothly distributed across the cluster, why are the galaxies themselves not? But then, I’m not Einstein, and seeing is believing I guess.
Dark matter has never been detected. It’s just assumed to be there, else the current theories have to be thrown out. We know how well “scientific” authorities on Earth respond to having their prestige threatened. Galileo would tell you.
The dark matter theory seems like a theory in search of evidence. It could be that there is just much more dust than current theories estimate.