It can't be avoided that's why you can't blamed authorities if they found mixing service as illegal. Mixing coins is considered as great tool for those institutions who wants to do illegal activities. It can't also be regulated since it's hard to track for a mixing company that the coins involved are being used to illegal activities.

Want to see Chipmixer's stand for their long term goals as this statement of Bitmixer really stick to my mind; "I hope our competitors will hear our message and will close their services too."