Some of the time, companies think it works. I have no faith in how much/whether companies track the number of times a user simply closes the tab because they got a shitty popup while they were trying to _read about the product_. (It happens to me all the time: Hit a product page, semi-curious, I'm reading about it, then BAM, a popup asking me to sign up for a mailing list, so I close the tab and move on.)

Companies are far more likely to say "We got X people signing up for a mailing list, it must be working", and don't bother whatsoever to measure (a) how many of those signups are just bots and (b) how many potential customers they just turned away by nagging them. I would bet any money that these metrics are either not measured or simply ignored.

This rationale right here is why we are stuck with so much bloatware. "People enter the tarpits all the time and never leave. There must be something there, I'm going in"