That is obviously a very relevant question. Given the downpour affecting the area the weather radar must have been lit like a Christmas tree...
Why did they fly into it?
Also relevant is where was this encounter during arrival? What could ATC radar see, or was weather suppressed? If it was, and the a/c is at low altitude, the onboard Wx radar can become cluttered with ground returns. On various occasions, in Europe, I asked ATC for weather avoidance assistance and they told me they couldn't see much, but my scope was showing unfriendly returns. Problem was I wasn't so confident what was ground return and what was lumpy bumpy sky. Under vectors I sometimes refused them and requested places that I could see were clear. An ATC controller can tells us what they can see for real.
However, descending into Orlando, the choice was taken from me. The weather was so bad that ATC had to re-route all arrivals & departures round some severe stuff, and they could see it all.
ATC are responsible for terrain avoidance and concrete clouds. What responsibility do they have for CB avoidance?