In the 70s when I had my two, I started with Terry's and when we moved to Sweden just after my DD was born, it was impossible to get, Napisan, waterproof pants, nappy pins etc because it was all disposables. Magic. What a relief.
Yes the question of long term degradation of disposables, but in the big picture there are many, many other areas where long term deterioration is far more dangerous for the planet.
So given the life style of young mums these days, give them a break, a few months of using these nappies is forgiveable.
The only drawback is the durability of them, and as mentioned earlier, this delays the child becoming dry early. Just get on with potty training earlier, take off nappies in summer etc. My daughter was 11 months when she was dry and this with using disposables.