Well usually the framework requires a plug-in and the plug-in requires RTFM which not all developers do. Also these frameworks and their plug-ins change and have their own dependency management that can cause code rot in short order that leads to accessibility or functionality falling off quickly. The solution to this becomes smoke testing for these already solved problems. Standardizing on built-in behavior makes testing all of this functionality the responsibility of someone not on your payroll or Jira board. I get that this isn't always going to be the solution, but that doesn't mean our code still needs to follow patterns developed to support Internet Explorer.
