The argument, at the time, and probably in the minds of many still...was that Apple was doing this as a means of making those affected iPhones feel slow so that people would be more likely to buy new phones.
Let's imagine that Apple had done NOTHING, instead. By doing nothing, the affected models would shut down unexpectedly once the battery had significantly degraded. Or the weather was too cold, etc. THAT would have made those phones more likely to be thrown away, less likely to be used long term, and more likely to cause the owner to buy a new phone.
Had Apple done nothing, the lawsuit wouldn't have existed, and those phone owners would have had a worse experience.
This is the definition of frivolous lawsuits and simply an example of how the media can whip up people to believe the exact opposite of what is happening.
Enjoy your $92.17.