I think that quote refers to the 3 gigabytes of RAM of the Librem 5 that was mentioned higher up in the chain, not the 3G wireless technology:
> But you pay 750$ for a 3GB quad core phone
Both Librem 5 and the Pinephone support LTE, although no 5G.
You are entirely right that phones which don't support LTE will have major usability regressions very soon so when you buy an older model phone you should really watch out to buy LTE capable ones.
Is it really?
AT&T and Verizon, two of the largest mobile data conglomerates in the US, have stated their intentions to shut down 3G service in favor of 5G by February 2021 and December 2020 respectively.
https://techblog.comsoc.org/2019/02/22/att-to-shut-down-3g-n...
https://stopthecap.com/2019/08/01/verizon-delays-shutdown-of...