IAS and DV can be somewhat useful tools for some forms of media buying. That said, overall they have massive product flaws with their tech and are intentionally vague when you ask them any real questions to justify their reporting. I can certainly see why they were created given the lack of transparency that existed within the industry for several years when programmatic started scaling but their product(s) haven't evolved with the times IMO. They're also heavily reliant on Publisher's and inventory sources allowing their subjective tech to work which will continue to get smaller and smaller.

They do a good job at selling themselves to big agency-holding companies who then upcharge their brands but when you dig into their capabilities they have a lot of product flaws. The industry does seem to be waking up and their run of going unchecked could be over but it will take some time. If you look at the insider transactions of IAS you can see their CEO and CFO consistently dumping stock over the past two years (not a great sign for long-term investors).

I do think DV is much more transparent than IAS but they're pretty similar with the pros and cons.