Installing a previous version of Captivate

With 2019 (v11) just released, that's the only version available to purchase.  We have clients that require us to build in previous versions (2017 / v10) for the current case.

I talked to Adobe support and found out two things:

1. The subscription model only allows the use of the current version.  So now it's 2019, no 2017.

2. They just changed the policy on perpetual licenses, so if you buy a license of 2019, you can no longer call support and request a previous version serial number.

Any one have any insight on this?  It really messes up consulting companies and freelancers as clients we may be building for hold off on upgrades quite often and require using a previous version, and if we don't already have it or add staff, can get them a license to perform the work. 

I know the creative could suite can load previous versions for items like photoshop etc, curious why captivate won't.

This is a little crazy, i'm sitting here needing to spend money with Adobe and they don't have the ability to sell me Captivate 2017.

Thanks for any help,

-jim