You are comparing the old simple "Remove Ads" option to Sync Ultra features.
The new "Remove Ads" without additional features costs 14,99 €. Which, yes, is more expensive than before, but that was to be expected. The old price would have been way too cheap for today's pricing situation, especially since he also lost most of his userbase.
I don't think the article is trying to claim that labor exploitation is new.
This part directly admits that it is a very old phenomenon:
It’s been noted, and correctly so, that entertainment industry labor disputes often erupt when there’s a change in technology — from theaters screening projected films to the cathode ray tube of the home television, say, or the rise of YouTube and other online content in the 2000s — and that happens for a reason. Historically, executives and management use a disorienting new technology to try to justify lowering wages of their workers, and they have done so since the days of the Industrial Revolution.
As I understood it, the article just wants to explain why this is happening now, because historically it seems to happen in waves.
The price was set many years ago and just never changed.
Also yes, less customers means less income for mostly the same amount of work. That is literally why bigger companies can offer cheaper prices. Scale.