Maybe the thing to do here, when web sites start enforcing this, is to swamp them with support requests. Don't write a screed or manifesto with ethical or technical reasons why this is wrong. Pretend to be a non-technically-inclined user and tell them you've spent hours trying to get it to work and your browser keeps throwing up errors you don't understand. They will ignore the principles, but if they think the technology is "too hard" for their "dumb users," that might carry more weight.