Nostr can't, and should not, prevent anyone from naming their account something, ever. The best practical solution we have so far is NIP-05 where someone can verify themselves with their own domain. As you mentioned in other replies, many people use third party services to set up their NIP-05 verification and yes, people can most certainly use it to impersonate you. I don't know who you are so I can't ask you IRL which third party provider your real account uses. There has been some attempts at web of trust and the like but I don't remember any practical solution that has been implemented across the board that actually works well yet. Other than a proper NIP-05 setup, the second best way is to verify through other channels such as social profiles, websites, and endorsements from other users you trust. E.g. when nostr started to take off (early 2023), I found good use of services such as nostr.directory where people had verified their nostr pubkey in a Tweet. When prominent and well known people have joined nostr, I have always been sceptical but accepted it when I saw people I trust confirm that it was a real account. It's not a perfect solution but so far it has worked pretty well for me, and I'm excited to see which solutions we come up with for this over the next 10 years.