No way. The data is quality-controlled and bias-corrected before assimilation. Any bad data is thrown out. The papers I linked above do a good job describing how this is done.

> What if joe forgets to maintain his station?

No maintenance required. Individual data points are irrelevant, this idea only works if you can throw out bad data without caring. So throw out any suspicious data.

> How do you assert quality control?

Sorry to keep directing you to the papers above, but a team of really smart people spent years on this topic and they do a better job of describing it than I could. Cliff Mass et al.

> I just am skeptical about this all.

AFAIK the Weather Channel has been providing your forecasts for some years now in Apple and Google products with all of this barometer data from phones and weather stations in backyards. If you didn't notice a strong quality decline since some years ago, then I would say it's fine. You've probably noticed a forecast quality increase during this time I'd guess.

> cant trust users phones to provide input for mission critical weather forecast models (GFS).

Why not though? What is wrong with any of this method? It is all scientifically tested, researched, peer-reviewed, published, analyzed, post-event-analysis, the whole deal.

> Peoples lives depend on this information!

Well yeah, that's why we need more data! We have so little data now that people are dying from preventable cases like a lack of storm warning or good communication about incoming weather events.

This all matters so much. Ignoring billions of deployed, internet-connected barometers is costing lives that could be saved if we used all the data available to us to make accurate weather predictions.