Yes - the feed providers should fix their feeds !
But when even NASA can’t get it right on their Curiosity feed (https://mars.nasa.gov/rss/missionupdates.cfm?s=msl), maybe it actually is rocket science… or maybe different standards (inches / cm , HTML / XML) is just an organisational problem they have. At least only RSS readers crash in this case.
Plugin simply edits the feed to replace any named entities (e.g. ) that aren’t valid in XML with their numeric equivalent.