That's another bunch of crap from MXA.
If the sliders are going to wear out, it has nothing to do with the chain, unless they decided to put a larger chain than the sliders are made for.
There is nothing wrong with the chain, but there is lots to be desired for what MXA knows about anything, let alone proper chain maintenance and recommendations on chains.
I hate to sling mud at a business, but in MXA's case, exceptions must be made. The influence that MXA has on folks is amazing.
When they run out of credible information they get from credible folks, they start making stuff up. If they aren't making stuff up, they are printing things spouted from kids who have nothing but high dollar two-stroke oil and gangstah rap in their skulls.
All you young YZ riders should steer clear of MXA, if it's credible maintenance information you are after.