Block buttons are genuinely valuable for public safety.
kiwi farms is the most notorious of them, but there are many groups dedicated to targeting and harassing people of various demographics with the sole goal of tormenting them until they commit suicide. And they succeed far too regularly.
Communal blocklists go a long way toward negating this. Obviously they aren't the most public, but various groups and "trusted allies" more or less share the users they block and why. I was involved with one for reddit and we are likely to set another up for the various subfederations (?) of Lemmy. The idea being that if someone triggers a red flag or two, you block them and then post their name and profile link into a google doc or a discord channel or whatever. And people either vet each entry in the list or just run a script to apply the entire blocklist to their account. So only a limited number of people need to see the assholes and people are less likely to find their feed/comments section/whatever full of people telling them to kill themselves.
Get rid of blocking and you remove that ability and people just have to "sit there and take it". Which... has horrible consequences. Because it doesn't matter how "strong" you are. Being told you have no worth and should end your life endlessly for months on end will wear anyone down. And while he was a right prick who did more than his share of damage, Total Biscuit put it best: (paraphrasing) You could be having the best day of your life. If someone tells you that your nose is ugly, that sticks with you.
And these hate groups make sure that those negative thoughts are all that people can think of.
And considering musk's hatred for trans folk and minorities and the like? He knows this and this is what he wants.
I can imagine people feeling safer, when they are able to block someone stalking them. When you mute a user, this user still can see your profile, your posts and simply knows that you are there, active, posting. On the other hand, when you block another user, you don't exist for this user. I don't remember if a blocked user sees a "you're blocked" message or if your account vanishes completely when the blocked user is logged in.
I guess people who have the habit of harassing other people on social media often have multiple accounts. The feeling of safety when blocking such an account is certainly real but if someone really wants to stalk you he can. Instagram tries to solve this problem by having the option 'block this and all associated accounts'.
I feel like it could be considered dangerous for some people. For someone who faces harassment regularly, taking away the option to block people means making them choose between a) dealing with constant online harassment, or b) leaving the only online community you know. At the very least, this change will be severely detrimental to some folks' mental health, while providing absolutely no benefit to anyone.
It could also be a public safety risk because twitter is a place where many people get news about natural disasters and severe weather. The people who are forced off of the platform because of this change will lose a valuable aggregate of information, and when it gets removed from app stores for violating their TOS (they require that social media services allow blocking), even more people will be without that information.