[Spare_account]

Everyone (talking about non-technical users here) won't understand why they can't message a particular person any more and will blame WhatsApp "It's broken again". Block by default would kill growth and they don't want that.

[eridius]

It also absolutely would create fatigue, I don't know why WhitneyLand thinks it wouldn't.

[WhitneyLand]

Because you only have to block once, explain the consequences, and then allow them to unblock by default.

[eridius]

At which point 99% of people would immediately unblock by default and the supposed security would be lost.

[WhitneyLand]

Maybe a lot would it turn it off, but its better than the current situation because everyone would know exactly what they're getting themselves into. Most importantly, the people who are most at risk would get a chance to understand the issue and leave it on for their protection.