A few people are online playing occasionally and updates are still coming out although the site doesn't list them, but as far as a large community goes, don't get your hopes up on that.

Sorry, I'm not too familiar with the 100dp format, most of my experience comes from 250-300dp decks. My general impression was that passcode swarm was the most popular deck and comprised of the majority of the metagame.

If snowball/multi-follower buff decks are popular, then yes, this deck will have a field day with them. If the majority of the metagame at 100dp are these kinds of buff decks, I can see why the op would think this deck is one of the best, since it does counter them easily. The deck isn't the strongest by far, but it does fit into the metagame.

No, it doesn't work like that.

Let's take a common scenario against a swarm deck.
You play a 0/2/11 and a 4/1/10 like you mentioned. Your opponent plays four followers and buffs them to 8/0/8's on average. Your followers each get attacked 3 times on average, 2 from enemies and 1 from a counterattack, and that kills both of them. Now what do you do?

You can continue to stall, or steal/remove.
If you stall, you're either playing followers that die in one turn like I just described, or not doing anything since your deck has no healing or deactivation cards. Either way you're going to take damage, and waiting for your opponent to "overbuff" is likely going to cost you a third to half your health pool.
If you start to steal/remove the enemy followers, you're likely trading 1 for 1. You can't play more than 2 steal/removal a turn most of the time, and your opponent has 4 followers out. So, you will steal a 8/0/8 or a 12/0/12 follower on average depending on how much your opponent buffed in 2 turns, and that follower will trade with your opponent's follower with the same stats. This just resets the board state, which lets your opponent build another board again with buffs. That's what swarm decks are good at doing.

Depending on rng, this might vary a bit, since you are giving your opponent a useless follower a good amount of the time, but on average your followers will simply trade. Now you're back at the start again, except you probably lost a third to half your life in the process, while your opponent lost around 5hp. Your opponent rebuilds their board, the cycle repeats, and you die at the end.

Defense buffing is almost negligible, most swarm followers have 0-2 defense, which means you spend 3-5 turns of doing almost nothing to steal a follower that will likely die on the following turn, most likely taking 8-10 damage in the process. Eventually you will run out of removal and keep drawing followers that are dead to your opponent's board and lose.

The only way I can see your deck feasibly winning is if your opponent has no idea what they're doing and buffs their board to some ridiculous state like four 20/2/20's and you steal 2 of those, then get some good rng to kill their other 2 off. However, as soon as your opponent sees a single piece of removal, they're going to be incredibly wary and won't overbuff their board. The entire premise of your deck becomes invalid at that point. You might win once against an unaware opponent, but I have a very hard time seeing the deck winning twice against the same opponent.

Generally I feel like you only thoroughly tested the deck against stall decks, which you stand a good chance against just by having child laev as your character (child ginger is almost an auto-win), and only played a few games against buff decks without testing out a large sample size. Otherwise your opponents might have not known how to play around your deck and kept falling into the same trap over and over again. I just can't see it winning consistently against a good opponent using a standard swarm deck.

As a side note, if you really want a HARD counter to this deck, it's easy. Play against an EX2 50pt character with all on-faction followers in their deck. Preferably an academy debuff deck. Fun times will ensue.