There is a team of people working on your website. They do research, learn what are the expectations of visitors. The team works on information architecture, navigation, how articles, steps, forms or data are presented, what comes first, what is the priority. How to fit all of those things on a tiny screen, but also make it look magnificent on a 4k display. Hours of work put into finding the right flow, guessing what user is trying to achieve.
And then someone decides that a pop-up with newsletter subscription or a chat with a consultant is going to be helpful.
If you think that what people find relevant is newsletter subscription or a chat — skip all that website production process and just do newsletter subscription and chat.
Think about it for a second. You launch Netflix, the beer is cold, the lighting is set. The chair is comfortable. Movie starts, tension rises, plot seems legit. Put a chat window there: “Hi! My name is John and I would love to know how do you find this movie on Netlix. [Start chat]”. No! So why doing this to your readers, customers, friends. Why?