THIS is what happens, explaining why people see this phenomenon over and over:
Deck X (enemy deck you can't beat much, e.g. Murloc Shaman) is popular in rank n
You lose to it a couple of times, you are now rank n + 1.
You lose to it a couple more times, you are now rank n + 2.
You decide to tech against it.
Deck X is not popular in rank n +2. You now face decks who are in rank n + 2. You may or may not be good against them. You do not see that old deck because they are popular at A DIFFERENT RANK. Also, because they are doing well at that rank, they are moving to rank n - 1, and then n - 2. You do not see Deck X at your rank n + 2. You do not see Deck X at n + 1. You also don't see Deck X at rank n, where you were before, because they are now ahead of you.
You face a bunch of different decks, who you are not teched against. You adjust your deck to face them, and then move on to rank n - 1, and perhaps to n - 2. You then see a bunch of those decks again, and then come here and complain because you see a bunch of that deck again once you removed the tech cards.
It is NOT a feature of matchmaking designed to screw YOU (Blizzard doesn't care), it is the meta at a micro level with a shifting balance over time. Anything else is just natural statistical variation within ranks.
There is NO conspiracy. Get over yourself. Play to beat whatever you're facing, and you'll rank up if you pilot the deck well.