Why are these things always The Biggest Update Ever.
If that were literally true, by now we'd be walking around with devices the size of Mt. Rushmore.
You're not wrong. The video video on Youtube gives a very good (and quick) overview of the marketing behind phone screen glass marketing claims; https://www.youtube.com/watch?v=7YrdI7h2XoY
The same will apply to everything any company is marketing, at the very least it will always be their 'best' 'new' product.
That's just the nature of (slow) exponential gains. If the processor gains 1% in flops each generation, the absolute flop increase is always the largest ever. Now consider that a device has tens of marketable metrics and that is always a defensible claim.
"We just changed a couple things, no biggie, don't buy it" is the reality, but that doesn't sell. Marketers optimize for sales saying what they can get away with.