So, nostr:npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6, the founder of Nostr, now uses a client which randomly adds meaningless "e" tags of type "mention" when he replies to a thread, pointing to some previous item on the thread.

The standard thing for a client to do when displaying such posts would be that of showing the referenced note as a quoted note. I don't think this is the intention.

Why do client include tags that make no sense?

See this posts for instance:

nostr:nevent1qvzqqqqqqypzqwlsccluhy6xxsr6l9a9uhhxf75g85g8a709tprjcn4e42h053vaqqsyrugq33u5gmnzlm74k3ke974txvg2xkgfdsdz8gufxfkh4x37xvcg8764u
nostr:nevent1qvzqqqqqqypzqwlsccluhy6xxsr6l9a9uhhxf75g85g8a709tprjcn4e42h053vaqqs25gcgd4c8356tlhl2wgrefhh6s0hnzedmhcsjgz6xhp4h2mvc2ng0urenl
nostr:nevent1qvzqqqqqqypzqwlsccluhy6xxsr6l9a9uhhxf75g85g8a709tprjcn4e42h053vaqqsg3szzyxr2ckav425thg2ygelf0xhspwrcx5chwrc6yjw2wgkjfqcuu4ck2
nostr:nevent1qvzqqqqqqypzqwlsccluhy6xxsr6l9a9uhhxf75g85g8a709tprjcn4e42h053vaqqsqsk3wnha6cl0x2p6x70p09pyze483509el9rup6ytjaj26kydjvqv9zfrf