Those advantages don't appear on metrics and therefore don't exist. If the benefit to the business is in two years and isn't measurable, the benefit it would bring will be misattributed to whoever happens to be around afterwards using it
That depends on context though. Sure, in a company driving for profits those metrics almost certainly won't exist. If the project is focused on end user experience, though, they would.
Accessibility is one area I've seen an overlap. It is still rare, but I have been on a couple teams where accessibility was a metric and it largely lead to better DOM structure and semantic HTML.
Quite true, unfortunately. But I think there are benefits that can be "feeled" almost instantly. I think problem is one of focus.
Lots of team leads don't focus on these solutions and their benefits but rather on the most recent technologies and their own benefits while ignoring (or accepting as inevitable) their costs. The longer you look in that direction, the harder it gets to see what you are missing or could get by looking elsewhere.
