It is tax sheltered true, but is your money and it's perfectly legal to invest in legal things if your plan allows it, not the government.Its not your money - its your tax sheltered money. As long as its tax sheltered the government gets to make the rules to protect most of the public. Should a wall street no moral hazard managed fund provider be able to stuff granny's retirement account full of meme coins?
If you want to invest in non traditional things its easy. Take your 401K money out. People on this board are always complaining about the 401K rules. They don't want 401K's or IRA's. What they want is tax free status on their investments so they can run their private individual hedge fund. ie they want their cake and eat it too. Pension funds never had that ability either.
https://duckduckgo.com/?t=ffab&q=Brokeragelink&ia=web
Sure .gov makes some rules, but again. Your money. The gov protecting the public? OK whatever.
You don't have to take your money out.