It is completely true, majority of it is just waste of your time, you may not be spending any money on them, but you are spending your time and time is something we can't get back. I would even rather spend money on them unless it is a huge amount instead of waste my time, because I can lose money and then keep working and earn that money back, money can be earned anytime, but I can't get back the time I wasted on these stuff.
This is why when you are joining an airdrop, do not consider your time cheap, doesn't matter where you live or how poor you are, you should instead spend your time learning new stuff which would be profitable for you on the long term. I agree that it is not that easy but it is definitely not worth it.
but then again these project never promise that they will have an airdrop, even allocation isn't even disclosed properly into the public so I don't think its really problem coming from their sides.
also added with the fact that sometimes most of the devs outright refuse to have plan of airdrops though sometime the ending is different but it seems they just don't want to take responsibility of giving airdrop.
therefore I think if anyone really wanna get the airdrop then just do the task, but never expect anything from it, airdrop was never sure way to make money in the past and its the same nowadays.
if someone want to make money for sure why they are not investing instead? though i know the result of airdrop sometime massive but its just 1 out of 100 projects out there even less.