Google has requried a phone number for registration for a long while now, and blocks many types of phone numbers, including almost all easily-created ones, making creating new Gmail accounts rather difficult without a trip to the store to buy a prepaid SIM.

(In many countries, including soon the USA[1], you can't get a phone number+sim without showing ID, also.)

[1]: https://reclaimthenet.org/the-fcc-wants-your-id-before-you-g...