It is ok, the complainers don't live somewhere where the trains have wide ranging routes and service that can be faster than driving. In those cities, I don't know that a shared ride service is a threat.
Here in Chicago, you pay a premium to live near a CTA line in the city (or a metra stop in the suburbs). Living near one means you don't have to have a car (or maybe your family can only have one car since you don't need to make separate commutes). When people look at jobs or new homes, they factor in access to public transit so they don't get stuck in situations where people say "oh, I could take the bus, but I would have to transfer twice and it takes 3 hours". I have the option to take 4 different routes to work: Motorcycle, Bus, Bicycle, Train. I live a short walk from the train and right next to an entrance to Lake Shore Drive (basically a highway straight to downtown) so I can take an express bus that gets on the highway and skips stopping in the middle.
The difference between this is mostly a tossup. The motorcycle is faster in the summer unless traffic is randomly bad, in which case it is slow (and once school starts in the fall, I think a lot more parents start driving again and traffic gets worse). I am able to sneakily park the motorcycle for free, but I would be paying $235 a month to park a car. The express bus involves very little walking and I always have a seat and can read, but it is subject to the whims of traffic and since it does make some stops, it will never be faster than the motorcycle. The bicycle is quick...I am a fast rider, but I can probably beat the bus unless there is zero traffic (and we have showers at work, so I just leave earlier and shower in the office instead of at home). The train requires a bit more walking on either end, and I usually don't get a seat in the morning, but it is consistent rain or shine since it is not subject to the whims of traffic, and it takes about the same time as the bus on a low-traffic day.
Where does an uber car pool fit into this? I occasionally take a normal taxi or uber/lyft if I am running late (or if the motorcycle isn't working) since by the time I am "late", traffic has lightened up. But if it were some alternative car pool scheme where they had to drop off extra riders, I don't see the advantage over the bus or train. The public transit options are already almost as fast as driving through traffic. If you add in the time to drop somebody else off or wait for a pickup...you aren't gaining anything. The fact that a regular Uber X/Lyft is significantl cheaper than a taxi (which I understand is not the case in NYC), does mean that I sometimes use transit less, it doesn't replace the 2x a day I use it for the commute.
I can see it hurting the crappy public transit systems in smaller cities where they have mostly been relegated to the poor...but maybe at that point it is really becoming purely competition for the local public transit. If the local public transit makes you transfer between two buses that only come twice an hour, and this can get you an "app-delivered" car pool in 10 minutes (and then skip the transfer)...then maybe these things deserve to win (or at least kick the local transit into action).