The Cura 4.9 release will have expanded functionality. If you have a plug-in that uses this functionality, marking it as using SDK 7.5.0 will notify older Cura releases that they can't use that plug-in.
In preparation for release of the 4.8. CURA-7795
CURA-7641
As explained in the comment. We reverted a change in 4.6, so we must unrevert it in master again. Contributes to issue CURA-7420.
