smaller diameter chain rings (and consequently larger cassette rings)
The larger cassette sprockets are not
consequent to the smaller chain rings in that they don't compensate for them. Making the chainring smaller results in a lower gear, as does making the sprocket bigger. They
both result in lower gearing. Put together they reinforce each other and give super-low gears.
There are two factors at work.
One: The trend for reduction in the number of chainrings - fall in popularity of triples (some of which have a
very small smallest ring, but it's on the inside so you can't see it) and introduction of 1x single chainrings. Arguably this trend was manufacturer driven in order to shift new kit.
Two: An overall lowering of gearing - or more specifically, lowering of the bottom gear. A reduction in cycling machismo that tough cyclists ride super high gears.
Put these trends - fewer chainrings and lower gearing - together and if you want to get a
really low bottom gear you need a teeny tiny chainring and a massive big sprocket. But if you look at these cassettes they also have a teeny-weeny 11 or 10 tooth smallest sprocket to give a usably high top gear.