I don't see it that way. It's much the same as a developer releasing a patch for, say, a real-time strategy game that happens to make it harder. I don't think anyone would consider that unfair to players who bought it later. Besides, the developers presumably think the added difficulty makes the game better; if they're right, low-level players have an advantage.

Also, a subsidiary point: front-line players seem to pay a tax of sorts. The first people to increase their Archaeologist quality had to pay for it; later, it increased automatically as we went on Expeditions. I actually started playing Fallen London a couple of years ago, and dropped it when I saw how staggeringly expensive PoSi stuff was. I have vague (perhaps fallacious) memories of some components costing 10000 Cryptic Clues each, along with a bunch of other stuff.