I really like this approach for 4 reasons:
If groups are maintained centrally they are always in sync. A common issue companies have is that they maintain a bunch of “lists” in different tools. Your VIP customers in your email marketing tool will often not match your CDP or push notification tools. Having one truth here is very valuable.
With the rise of privacy concerns and regulations like hipaa, GDPR, CCPA....more companies will want to control their data. Shipping PII or PID info to different saas tools will become increasingly dangerous. Controlling this centrally on your own servers offers a security and elegant solution.
Tools like segment and mixed panel are events driven. This is an old school approach vs just having all the data. They also charge based on events so companies must choose between cost and the fidelity of their data.
Make business users self sufficient. Almost any tech start up experiences the issue of business users needing to have engineering help them when they need a new data set. If business users are able to do this on their own it will make them more efficient but more importantly engineering will be happy to not always be bothered to write a new SQL scripts all the time.