There are countless modern PCs that have secureboot enabled by default. Does that mean all their users endorse and agree with secure boot based attestation knowingly?
My point is defaults cannot and should not automatically be treated as implicit consent/knowledge.
Attestation will be enabled by default when Chrome ships WIE and the "majority" condition you mentioned will most certainly be true from day one. That doesn't necessarily mean that every single user of chrome is onboard and happy with WIE.