To be honest I am in two minds about this.
The obvious retort to the OP is 'Valid for what?', or 'valid according to which standards'. Given the reference to the equally arbitrary site speed, or the oft disputed W3C, this gives some indication that it is entirely opinion based. This would be better suited to a forum dedicated to HTML or contractual issues, not for the Freelancing stack exchange.
However, if the site continues to reject 'advice' or 'opinion' based questions, I am not sure what it is going to answer. Most valid freelancing questions are never going to be black and white. It will often be not like a maths question or a coding question, where an actual 'right' answer is available.
I can point to lots of great questions on here that could equally have been rejected as opinion based.
So I am in two minds, and although I think there is room for more grey and less black and white on this channel, I do think this question probably overstepped the mark in this instance.