There's nothing strange about the behaviour at all.
It's rather expected actually. As Nij said in the comments, the first day will have a lot of excitement and then things will settle down. And while there isn't as much of a burst of new users, there is still a steady supply of people pressing the follow button every day. The problem seems to be more that new followers on the proposal aren't voting.
Well let's take a look at how the journey of someone coming to the proposal with no knowledge of how SE/Area 51 works.
This person will see a cool post on a place like reddit (because there are relevant programming language design focused subreddits that exist - and yes, a SE site can coexist with subreddits because reddit is more of an informal site while here is a very organised and structured question and answer system). The post has a title which is written to contain the bare minimum to get people to join the proposal (less is more) and a link to the proposal page.
Once they get to the proposal page and they struggle with the area 51 account creation process (which quite a few people mentioned was an issue), they finally click the follow button. After that, they see a list of top questions and think "hey those are cool I'll upvote them." At no stage have they been informed about the finer rules of site creation and there's a good chance that they never will be informed because they're here for one reason and one reason only - to click a single button.
Now sure some people might be interested in exploring the rest of area 51, but for the most part, humans are somewhat lazy. If there's already been a lot of effort to accomplish something that they think shouldn't take much effort, chances are they won't come back for more on their own.
Every person from an external site will go through this journey and either successfully follow the path described or give up at the start because of the difficulties of actually interacting with the site. That explains why there's a whole lot of followers, but not many 10+ score answers.
But that's not the only factor at play. There's still 2 more things to cover: the Fastest Gun in the West effect and strategic voting.
The Fastest Gun in the West (fgitw) effect is something that has plagued Stack Exchange sites for years - the first answers to a question will be massively upvoted and seen, but later answers will fall by the wayside because of things like default sorting by top and the high visibility of the existing answers. That means that late answers which may be more accurate or correct than the existing answers may never be seen or given appropriate recognition. This effect also applies to the example questions list - the top questions are the first thing many people see, and the pages of 1, 0 and -1 score questions are never looked at because they're hidden away.
As mentioned, there's also the consequences of strategic voting. Due to the decision to only allow 5 votes per proposal, people dedicated to getting the site launched will move their votes around to boost the scores of lesser seen posts. So a question that reaches 10 score will become a 9 score again, even though it once counted towards the required question count.
In conclusion, it's really the result of the site not really being that well suited to onboarding new users in a way that effectively communicates the fact that voting is important. Sure, people can investigate for themselves, but unless it's explicitly spelled out in the original advertising on other sites (which there's a chance it won't be because who wants to read a whole bunch of intricate text on an advertisement), people will just click a button and leave. And then on top of that and the struggles of signing up (see here for an example), voting is going to be impacted by simple physiological effects that can't really be mitigated. All one can do is just wait for the votes to eventually make their way to the right place.