1) This article links to Visual Studio C++ 2012 runtime, but the KB article (https://support.microsoft.com/en-us/help/4489622/cumulative-update-23-for-exchange-server-2013) links to 2013. I assume the KB takes precedent?
2) Other commenters referred to the .NET support table, which I didn't see linked anywhere, but I did find it: https://docs.microsoft.com/en-us/exchange/plan-and-deploy/supportability-matrix?view=exchserver-2019
3) The KB article states:
Cumulative Update 23 for Microsoft Exchange Server 2013 was released on June 18, 2019. This cumulative update includes fixes for http://support.microsoft.com/help/4489622#nonsecurity%20issues and all previously released fixes for security and nonsecurity issues. These fixes will also be included in later https://technet.microsoft.com/library/jj907309(v=exchg.150).aspx.
This update also includes new daylight saving time (DST) updates for Exchange Server 2013. For more information about DST, see https://support.microsoft.com/en-us/help/22803.
So, if we are up to date on the security updates, does that mean there's no compelling security benefit from this CU and this would only provide the non-security benefits?