Bending radius on cat6 is ridiculous,
and it takes about 3 times longer to terminate, plus it won't fit into a standard 25mm back box.
Then there is the price of a meter to verify it, they are crazy expensive, it's a lot even to just hire a very basic one.
There is absolutely nothing wrong with cat5e for most situations, and most people could install cat5e to an acceptable standard .
Very few, if any, DIYers could install cat6 properly, I've seen a lot of professionals get it wrong.
Saying it's an old standard is like saying nobody should have an internal combustion engine car ,
Having new technology doesn't automatically make older stuff obsolete