Yes. There is no way to authorize DP 5 or 6 after OS 10.6.8. Cloning, Migration Assistant, Time Machine – none of that works if you lose a drive or upgrade to a new machine. DP 7.24 is the earliest version that will.However, if a persons computer breaks, or if they need to update their OS in order to use some software, then they must make a choice.
I keep a working copy of 7.24 so that I don't have to run 8.07 in 32bit just to open certain old projects. Although 32lives has made even that mostly unnecessary, I still run into it now and then.
I really liked DP 5.13 and have it installed on my G4 but haven't fired it up in years. No point except to remove certain ancient plugins that a) never worked in OS 10.5 or b) were PPC only. I have a feeling that I may still have a few of those around ... perhaps not. I did learn to zip the project folder before moving a file from my G4 to my iMac. DP 7.1 and later are much, much fussier when it comes to privileges.