This service will provide a way for dapps to distribute gains among dapps' token holders.
The first user of this service will be the ErgoMixer.
Ergomixer's income (in ERG and other tokens) is currently received by its creator, aka 'anon2020s', since it has only one stakeholder at the moment. He has announced that he is willing to create and sell some tokens in the near future to obtain more stakeholders; let's call this token MIX. Later, anyone having the MIX tokens can stake these tokens in the Profit Sharing contract and obtain the mixer's incomes proportional to their staked tokens.
So, it is NOT a way to stake ERG at first. But, it CAN BE USED in the future in some creative services to provide ERG-staking.