This has seemingly become more and more common for couples and singles to use the block as a way to filter out people whom they believe do not match what they are looking for.
But it seems, at least to us, a bad way to go about it, and its rude.
One over the years we have found many times that those we wouldnt have immediately thought would be a great match turned into amazing friends, and we had the most amazing evenings and weekends with them.
So you are limiting yourself, and a quick, friendly conversation doesnt cost you anything. And if the people persist, despite a friendly no thank you then use the block. That was its intended purpose.
There are more than enough features already to help you filter your preferences without needing to use the block feature.
Just our two cents