"The root cause of these issues is therefore Microsoft's use of non-standard extentions"
No. It's the developers of the software who fell for MS bull**it and did so with wild abandon.
In 2000.
But it's 2017 and for reasons still unexplained those developers have not got their s**t together and made their LOB apps browser neutral, which would go a very long way to making the next move (and there will be a next move with MS rule, of turning over the user base every 18-36 months).
17 years.
BTW People have bleated on about this being a problem with various diagnostic machines. But these are a special case. IIRC Embedded Windows XP is under support till 2019. So why didn't the suppliers use that instead?