Agreed, but there may be ways around it too.
Just depends on what the tool is.
Regardless, if the engine works and is able to display something - which it is - then the official support doesn’t much matter does it?
Generally, if a user is on anything that doesn’t work, he’s not an ideal user. Particularly if 60% or more of the user base is covered.
With a little duck typing you’d also be able to serve browser specific versions to those who do not meet the requirements…