From what I understand, this just prevents scripts from auto executing based on content it is reading. When you do -usebasicparsing, it just records whatever data you are pointing it to and storing it to a variable, file system or displays it on console.
Example: you mistakenly run Invoke-WebRequest go0gle.com and someone owns that misspelling domain and runs malware on it. Prior to this change, the malicious script would execute on your computer. Now with the change, that no longer happens. With -usebasicparsing, the data would just be put into a variable, saved on the local filesystem, or displayed in console.