jm xþÙ¡áÎOסæ(ëI^ÉÍíÞ¹yÕúP³LGood point. However, PoW-based avalanche is more complicated, and it does not allow miners to come and go arbitrarily as they would surely lose trust.
https://whatsonchain.com/tx/939e9a99338001ac84b1148e83e7e65b442a8f71aa3259fcb894e048a554eb46