Nobody needs electronic groupsets.
Any reasonably well set up and maintained mechanical groupset will do pretty much everything pretty much any rider needs. Races have been won at the very highest level even in recent years on cabled groupsets.
That said, I think they provide a meaningful advantage in time trialling, where you can shift from the base bars (where the brakes are located), and anyone who has ridden a full season of cx will tell you at great length how much maintenance time they save you. Blips provide a real comfort advantage on very long rides too.
Moreover, the substantial majority of users really like electronic groupsets, for the reasons outlined in previous posts, and most don’t really want to go back.
Of course, there is always the possibility of a flat (or faulty) battery, and for some users and applications (bikepacking springs to mind) the perceived risk may not justify the reward.
For most road riders, I think range anxiety is massively overblown. Even if you only got 500km between charges, even very high mileage riders are only charging the system weekly, and it takes a few hours at most, probably less. Check the battery level on a Sunday night, if needs be stick it on charge when you go to bed, by Monday morning you’re all set. In real terms, most riders are doing this fortnightly at most. How often do you charge your phone?