Yes I agree with you, I don't want any random website to be able to query my phone to find out what apps I have installed either. However, if I'm on a specific

Yes I agree with you, I don't want any random website to be able to query my phone to find out what apps I have installed either. However, if I'm on a specific app publisher's website, I wouldn't mind letting them know (through some mechanism) that I've already installed their specific app.