Probably most everyone agrees 'citizen science' projects such as eBird.org or iNaturalist.org are a good thing. Species range and abundance can be recorded, and trends followed. Furthermore, people getting involved in the natural world may become conservationists.
However as these types of projects mature, some negatives are emerging. With eBird, which is heavily marketed, many beginners are entering incorrect data. It is impossible to say a sighting didn't happen, but many sites I've looked at have between 5-10% of species that I believe could not have occurred. Recently I've spoken with several birding experts who concurred.
More worrisome is that with eBird, some people are intentionally entering birds they did not actually see to advance their personal goals. And some sites are entering birds not seen definitively to promote their sites.
I don't have the solution to this, but I was impressed by the eBird-like project used in South Africa, called BirdLasser. It isn't based on 'hotspots' and doesn't seem to focus on personal list counts and competitions between people and countries.
On a related topic, Cornell/eBird right now is trying to become the Amazon one-stop of ornithology. They acquired in some form the rights to the data from Handbook of the Birds of the World, the premier on-line reference source. HBW.com is gone. Perhaps they bought this with money from t-shirt sales. The HBW product was excellent. So far I have been less impressed with Birds of the World. It is more expensive and in some places they replaced the HBW content with their own in my opinion inferior content.
One worry is that eBird might want to become the owner of the default taxonomy. I think this is best left to a scientific committee, and not a for-profit organization. I recommend the IOC taxonomy by International Union of Ornithologists which is totally science-based and with no obvious agenda. I can't publish their website because Facebook says it is SPAM, which makes no sense
The IOC database is used by Xeno-canto.org, another excellent scientific organization. Xeno-canto.org for example has no fine print that says that sound files uploaded can be used by them for any purpose, commercial or non-commercial.