I see two problems:
1. You can never be truly honest. Everyone has a side they don't project when their reputation is on the line. With a pseudo you can project it, and dump the name if things get too hot. Maybe your opinion is en-vogue today but worthy of real life harassment later. Maybe you are a person who belongs to a group of people that are not well liked. Maybe alphabet soup agencies want you. Who knows - all you know is you can't predict the future.
2. It encourages validation seeking behavior. Evidence: social media. Professionally, linkedin is a shithole of validation seeking losers posting below-the-fold faux-philosophy and/or corporate shilling. These people likely wouldn't do this if their identity was not attached to a face, an address, and a company.
Overall, it's a net loss to use your real identity. For the last 25 years I haven't needed to tell anyone online my real identity and I won't for the foreseeable future. I have plenty of friends on IRC and other places that only know me by my handle. This is not a bad thing.