From a (US) financial perspective, a phone charger takes about 5 watts of electricity. At $0.010/kWh that’s $0.0005/hr (or ¢0.05/hr) of charging. This is utterly negligible.
For reference, a worker at the federal minimum wage of $7.25/hr would be paid that much after 0.25 seconds of working. It’s not even worth paying an employee to tell you to not plug in, which would probably take at least 15 seconds.
Naturally, some businesses may want to discourage people from loitering, but more often than not, they probably want your business (library, grocery store, coffee shop &c) or understand that reality happens.
And Discord meshes very well with other social media. Reddit, Youtube and Lemmy communities all benefit from having Discords as well.