You're not the only one to have an issue with that particular "feature". I actually have a very low opinion of hubski specifically because of that feature. There's curating your own experience, and then there's curating others' experience and that's where it crosses the line.
It allows people to 'win' arguments by replying to the person and then muting them so they cannot reply back (and I cannot think of a specific time where someone didn't reply to me and then mute). If the person wants to ignore someone, that's completely fair, but the downside should be the person being muted having the ability to make their last point. Fair is fair, and just because someone doesn't want to have any interactions with the other person doesn't mean the other person doesn't have anything useful to say, or that others wouldn't find it useful as well.
It also negatively detracts from actual discussions. When someone can completely shut the other person out of the conversation because they don't like their opinion, or the way they choose to express themselves, it means the people in the discussions either have to trust the other person or tiptoe around constantly (or just not engage in specific types of discussions). There will be those on this site who will claim otherwise, but nothing I've seen here has really been any more meaningful than the sorts of discussions I find on reddit (and in many ways, much less meaningful).
Here's my opinion on the matter.
I've been on reddit for over 6 years, I've gotten to watch it grow. There was a period in Reddit's history where a lot of the 'old hands' would constantly complain about the newer users for 'dumbing down' reddit by abusing up/downvotes (upvoting cat pics, downvoting "actual discussion", that sort of thing). But because reddit is a completely level playing field, these old hands lost. The community as a whole wanted content that ran the gamut, from cat pics, to deep discussions of type theory (and this is what you'll find on reddit, an extremely wide array of content).
Hubski's design was borne out of this 'fight', it's why Hubski's overall design goal was to get rid of the up/downvote mechanism. The 'old timers' have more power on this site by design for that very reason because giving people more personal power was one of the goals, and say what you want about up/downvotes, it levels the playing field with respect to the visibility of content since everyone gets a single vote.
And you can really see that attitude in the culture on this site too. Being called a redditor isn't a compliment, for example. I've had people attack me for linking to an appropriate meme that described my feelings on the matter as well. Basically, anything that was previously considered to be a part of the aforementioned 'reddit dumbing down' is really frowned upon in the hubski culture.
The anti-reddit sentiment is so strong on this site, that the last 'influx of redditors' was met with a suggestion to be able to auto-ignore every account that was less than X days old, and it was seriously considered by the admins (I have no idea if they went forward with it or not). It was specifically a move against redditors. There are a lot of people who won't like to see it characterized in this manner, but lets call a horse a horse.
And the worst part is that the discussion is better on reddit anyway, but I'm sure that's just opinion as well.