RE: The need of Customer Insights in the Dynamics family
I've worked with several CI Implementations at several different companies so happy to add a few things.
1-If you have very few 3rd party sources and very complete data, CI probably isn't going to do a lot that you can't do already. However, businesses change and many companies have had to bring in a critical 3rd party piece of software that they never anticipated up front. Often integrations are done one at a time and accrue a lot of technical debt, CI removes a ton of friction you'd otherwise be stuck with.
2-Even if you have no 3rd party data sources and you ensured that you have keys for all the data, the nature of the data can be such that it's not consistent or complete. Obviously it's going to be more an issue with 3rd party items but this can absolutely happen with internal data sources. (Think Web Server logs being married up to your customer base.) CI Lets you grow without having to worry about 'how much of a problem will it be to integrate another product'
3-Your 1st party data sources won't always share keys so you have to handle that integration manually, which again is just technical debt.
4-I realize this is very similar to #2, but even if you have all 1st party data, acquisitions are pretty common. You can't know that you'll be acquiring a company in the future or merging or a lot more. Go through three or four of these and it'll get very messy. Many companies are an amalgamation of several acquired companies, all of which were 1st party but completely different.
5-Even if you have all first party data sources, they may be incomplete. Being able to enrich that data brings a lot of potential value to the table.
6-having a clean, consistent and low code way of synthesizing data and integrating it into other systems (without accumulating even more technical debt) is another one.