"I don't, so neither should you!" is a constant and reliable companion to "I did, so you should, too." I personally like to counter this wayward opinion with, "You're not the boss of me!" Or, if I'm feeling really defiant, "I'll damn well do as I please!" And, if I'm in a superior than thou mood, I will likely respond, "If you don't think it's right, then don't do it."
For the sake of discussion, I'd like to label this behavior, "I'm the boss of everyone" perspective. It takes the idea that if it's good enough for me, it's good enough for them, to a new height. This mode of thinking embraces the idea that what is good for me is good for everyone.
Individuality, liberty, and freedom of choice sit as the cornerstone of successful relationships. We must be free in our relationships to be true to our authentic selves and take actions in alignment with who we are and what we desire. The single most crucial caveat at play here is the ability to respect the personal boundaries of those we engage with in the process. Respecting other people's boundaries doesn't mean sharing their sensibilities. It means not forcibly restricting or forcing their actions and desires. Think kindergarten - Get your work done and keep your hands to yourself. The tricky part can be exercising your right to individuality while not impinging on the rights of others.
If you find yourself threatened by other people's choices, start paying attention to what it is you fear. Because where there is judgment and condemnation there is fear. When you find another's actions contrary and objectionable, it's because those actions either undermine your confidence in your personal choice or make you feel vulnerable regarding the likelihood of getting what you desire.
We are blessed to live in a free country. Our freedom in this country, and in our personal relationships, is anchored in our rights to free speech and freedom of association. If you don't think it's a good idea, politely decline to participate.