I don't really understand the video. Do they just not want people to use the term "power creep" in a different way than it's used internally? War Golem is used as a point of comparison against Dr. Boom as a jumping off point or an exaggeration, but obviously these kind of complaints should be interpreted as: "Dr. Boom is so powerful that it is ubiquitous across a range of decks that often have nothing in common with one another." These kind of power creeps often create a new level that few cards stand on the level of, if it is even more than one card.
It's only a few cards at first, but all cards that will to be created after will be measured against that card. It's less obvious with Boom as there are few 7 drops and 7's were weak before it, but think of Piloted Shredder. It was the top 4 drop when it came out, not accounting for specific synergies. Now, every time Blizzard makes a 4 drop, people are going to ask themselves if it's worth running over Piloted Shredder. In order to keep the game fresh, Blizzard has to release cards that are worth playing for one reason or another. That means that new 4 drops need to be near the level of a shredder, or better in certain circumstances. This means that one card has in effect, increased the baseline expectation for 4 drops. That is power creep.
For cards like Ice Rager, this doesn't happen because both it and Magma Rager are still shit. Neither card sees play, and neither one is in any danger of raising expectations and affecting overall power level. It only appears like power creep to people because the easy, lazy, profiteering way of creating expansions is to just release a bunch of similar cards to what's currently played, but better. If they didn't care about power creep, they could release 5/4 shredders, a 3/2 neutral mini-bot, or a 1 mana 2/2 Mad Scientist. People would play those, and it would raise expectations for card power going forward. People aren't going to play Ice Rager.
And the whole...bad cards existing to train players about bad cards...what? So is the intention of stuff like TGT and the implementation of mechanics like Joust to create a bunch more new bad cards? Does the game need a regular influx of bad cards?
If anything, Joust is an example of what can go wrong when you avoid power creep. The goal of any release is to create cards people want to own and play. To do so, they either need to replace something you already use (power creep), or they need to be something different. Blizzard's answer to power creep seems to be introducing new mechanics with each release. And they're generally going to try to match the power level of existing decks, not really beat them, because that would be power creep. But when you do that, you run the risk of a mechanic being a flop, which is what happened to Joust.
This is different than the argument being made in the video, which deals with bad basic cards. The idea is that progression is essential for new players. To stick with the game, they need to feel like they're getting stronger and better at it. One way is to have a few cards that have strictly better versions outside of the basic set. It's a trick since those cards are still crap, but a new player doesn't necessarily know that. They could get Ice Rager in a pack and think they have a stronger collection because it's obviously better than their old Magma Rager. And it's not something I noticed until he made this argument, but Ice Rager and Heckler are commons. It doesn't really fit any nefarious plan for making people get new cards because they're freaking commons and they're still bad. But it does affect the new player experience because they're going to have mostly commons at first.
I was not a fan of cards like Ice Rager, not because they were power creep, but because it seemed like lazy padding. But I like Brode's explanation and reasoning for it, and I don't see a problem with them burning a few common slots on tricking new players.