There are a lot of players in this market. Many that integrate with all the major CRMs and append and clean data.

I would say I get at least 1 email a day from a data vendor and I have been on countless demos and calls and because my client is so niche they never have more 5-10 records even viable for me.

I am sure for larger companies with broader markets this works well. They all tend to have very aggressive sales outreach. I have one company that has called me every 3 months for the past 2 years. At this point hes basically just asking about my health and the weather :)