You argument is misleading at best, dishonest at worst.
Mining is ONLY expensive on POW blockchains, not POS or POI blockchains.
I don't see how Electroneum is ground breaking. Why can't you use any of the dozens or hundreds of POS coins, such as NEM, Dash, Monero, Zcash, PIVX, etc. on your phone? Besides, phones are getting more powerful every year. There is no reason that phones won't be able to do mining for most POS and POI coins soon.
If you mine on a POW blockchain, the power of your pc/smartphone is decisive for the outcome. Good Pc = More Crypto / Bad Pc = Less Crypto. Most Smartphones can't handle the needed power for solving difficult calculations, it will fry the processor.
For Blockchains working on POS, the decisive variable is the amout of crypto you already own. If you own a lot, you get more "taxes" for it. If you're not the owner of a masternode, your pc doesn't really need much power compared to mining on a POW blockchain.
Electroneum has a interesting concept, mining on a smartphone is a nice way to achieve attention from people who are not familiar with crypto. What is important to know, the blockchain doesn't get any power from Smartphones who are mining Electroneum. It's only marketing, you basically get money for no compensation. They get their needed power from normal Desktop PC's and maybe gaming consoles in the future.