You can just ask people out. You can just ask to kiss someone. I was in my mid 20s when someone told me the first one, and late 20s when someone told me the second one. Dating got a lot easier after each revelation.
I agree with your comment in general, but it does depend entirely on the context and the situation. Eg, at work, you can't just ask someone out. That's a sure fire way to end up in front of HR.
I had the biggest crush on a coworker, but I stick to this rule like it's oxygen. I waited to ask her out until after we stopped working together. To my surprise, she said yes.
Right, and you shouldn't ask a married monogamous person out on a date, either. Never came up for me but is worth keeping in mind! A lot of guys seem to struggle with "she likes me bro she smiled at me" -> "my guy she's the cashier at work she has to smile at customers."