If I created an online service that charged a fixed small sum to include your btc transaction in next block and then mined btc myself, wouldnt it in theory be possible for me to get all and everyone to set the fee really low and then pay me the fixed small sum to have the transaction included in the next block rather then setting a high fee to have a random miner include it maybe and when they want to?
There is nothing wrong in having this kind of service and I think I was some service like that in the past that performs some free acceleration service up to certain point and then charge fee for those above the benchmark. You can then make it a more bigger one so we can patronize it.
I have used ViaBTC but now its seems the crowd on it is too much that they just increase the maximum threshold every hour.