Just people who don't understand F1. Mercedes have a obvious problem between on track data and simulation/design data. That was highlighted yesterday in FP2, when they made drastic changes to Hamilton's car and went completely the wrong way. Whether they used packer on the underfloor to try to change some airflow, isn't known but whatever they did was the wrong direction.
They are using Russell's car and setup as a benchmark and deviating from that setup to run experiments with Hamilton's car (more experienced driver), to see if they can unlock the cars ability as their off track data says it has somewhere.
They have a problem with something off track, three seasons in and they haven't figured out what it is.
So the average armchair fan won't know about any of this and it will be that he's too old or some other bollocks.
All Mercedes have to do is give him a competitive car, but 3 seasons into these rules they can't manage that.