The difference is that earlier, if there is a load spike in monitoring, we dont know if it was cause of 3rd party scripts or some problems with out server/CDN. the former we can live with, but the latter is very bad.
Now after deferring the 3rd party scripts, we know for sure what the user experience is with regards to the main content of the site.
Now after deferring the 3rd party scripts, we know for sure what the user experience is with regards to the main content of the site.