Just think about it: if entire rigs of dedicated GPUs are hardly profitable today, how is your puny smartphone going to make you any sort of money by churning a complex cryptographic algorithm??
The coin rewards you might get from these gimmicks they call "mobile miners" are a fraction of the ad revenue they get from forcing them down your throat while you think you're mining.
Sweatcoin is the best example. But hey, it works!
Just don't call it mining.
Yes. I'm aware of that. However, I still believe that even if mining with a smartphone is not profitable, it could further strengthen and decentralize a cryptocurrency's blockchain. Among the various CPU-only PoW algorithms I've researched, Cyckoo Cycle seems to be the most viable option for mobile devices today. If proven to be successful, then it could bring a whole new level of decentralization for the blockchain. People worldwide would be encouraged to mine a specific coin with the Cyckoo Cycle algorithm just to earn some spare cash, while at the same time, securing the cryptocurrency's blockchain.
aeternity is a good example of a Cyckoo Cycle cryptocurrency, but it hasn't launched yet. As for now, it's still an ETH token, but it'll be interesting to see how everything unfolds once its mainnet is launched for the public to enjoy.
This new coin you've mentioned called Sweatcoin looks interesting and reminds me of the good-old MangoCoinz. Every time you complete a certain number of steps (when walking), you'll get rewarded in that specific cryptocurrency. I believe this is good as it incentivizes people for taking care of their health.
Traditional PoW algorithms could easily shorten the life-span of any mobile device. However, there are some cryptocurrencies which make use of "Virtual Mining" that wouldn't pose a threat to your device's longevity. A cryptocurrency which uses such algorithm is called Electroneum which allows you to "mine" the cryptocurrency on your smartphone just by activating the app. However, it's not really mining since resources are not consumed in the same way it would be via traditional PoW algorithms such as M7M, or Scrypt.
As time goes by, PoW algorithms could be perfected at some point, where it'll be easy for anyone to start earning rewards and secure a cryptocurrency at the same time. With the launch of aeternity, things will change drastically as it makes use of the Cyckoo Cycle algorithm which is extremely efficient for mobile devices.