Basically, it’s to make sure you can securely connect to a whole bunch of websites and online services without getting blocked. Many services, especially older ones or those used in big companies, still rely on certificates from these guys (even though Symantec’s cert business is now run by DigiCert). Including them helps Fedora work smoothly everywhere, balancing broad compatibility with security. It’s not about Fedora giving a thumbs-up to these companies, just making sure things connect properly based on what the wider tech world trusts.
You can leave them be. Fedora would have removed them if it was an actual issue.