nostr:npub1u2hl9r48emg8eq82nh8zwadl3xr93u7vkk37qavfcg7cu3dmrrzqe4z4d7 

Because of all the things some can do if they have your cell number, 
Even if #Signal now does not link your phone number to any transaction, looking at the sudden TOS changes of the past months in BigTech (e.g. Zoom's on 04/01/23) is a clear warning sign that things can change with sudden notice. Lock-in is very high for a messenger app.
Also, in another convo, we were discussing the problematic use of Google services by Signal, which I cannot reproduce, as I am not a tech person.