Hi Kris, thanks for this reply.
So, warning, very minor defensive rant coming up here, not directed at you as much as all the people who have told me I don’t need blocking… 
I have done hands-on community management for a zillion years (even back when I worked for AOL, CompuServe, and GEnie doing community stuff in their message boards and chat rooms). Now I run a community site of my own. Forums are a part of the site and where a lot (but not all) of my site’s community interacts.
I totally and completely get the reasons why blocking isn’t great… I get it. I really do. I read every message I could find here on meta.discourse. I saw the people pleading for Ignore, I saw the debates back and forth about why it’s not a great thing, and I saw when y’all finally capitulated and added it to the software.
In all of this, I think some folks forgot that not everyone is running a site that is only Discourse/only a forum-based community.
In my current situation, I already had a strong community on my site before Discourse came along: not only in my previous forums (with their crappy old software), but also with the chat room feature on my site (which has its regulars and its own community that overlaps with my forums) as well as other community-centric features on my web site.
And for better or worse, my site has always offered the ability to do a “full block” of another member. Partly due to community issues, partly because the community I serve expects that I will be VERY sensitive to their privacy for a number of reasons, including legal concerns (seriously).
Asking the question “is blocking a good idea?” isn’t the right question for me to be asking at this point. Even though I personally don’t love the idea of blocking, that ship has sailed.
(A little more context: my old forums were pretty toxic due to decisions made by the previous owner of the site. Part of the reason people demanded a 2-way block is because of the crap in the forums. As part of my upgrade to Discourse and unveiling all-new forums, I’m also working on helping repair the damaged forum community.)
Again, to be crystal clear, I totally understand why blocking is generally not a great sign of a healthy community. In fact, I’m working on trying to get my members who were previously block-happy to chill a bit.
So.
If I were starting a brand new community, I would absolutely start with Discourse and wouldn’t need two-way blocking.
If I had a site that didn’t already have two-way block available (or I wasn’t upgrading from forum software that previously supported two-way blocking), I wouldn’t need two-way block in Discourse.
If my current forum community wasn’t already damaged, I wouldn’t need two-way blocking. But they have had some terrible experiences in the past that have demanded the blocking feature, which I had to implement. Now making the change to Discourse is a big shift that is shaking up the community already (it’s a lot different than what I had so it’s a process), and it’s not the right time to also say “oh and by the way, we’re dropping blocking.” I’ll have a revolt on my hands.
Anyhow. I apologize for the length of this reply and I hope I don’t sound too defensive. I just don’t want to get pulled into a philosophical debate about blocking and why it’s Not A Healthy Thing.
I still need a full-block feature.
I sincerely and truly appreciate all feedback and help! And part of the reason I’m posting all this (and taking the time to write out this crazy-long message) is because I am trying to contribute back to the Discourse community.
Let me end with this: I know Discourse doesn’t exactly offer what I am asking for right now. But it’s close! I’m not trying to convince the Discourse team to add it to the software (that conversation mostly started and ended long before I got here)… but I am trying to accomplish my goal with the pieces I have in front of me… and asking for help from the smart, clever, creative thinkers and coders I’ve seen around here… and sharing what I discover along the way with others.