No, I think it is totally unrealistic to expect software support and backup from any manufacturer after the end of its cycle.
For CS6 a product launched 9 years ago (CS4 and CS5 2 years older) with support and updates for around 9 years I think that is pretty good
Spending around £600 on a piece of software and not keeping backups including upgrade backups, and ignoring Adobe comments is folly
Note:
Important: Back up your downloaded software to offline media, such as a DVD or network drive. With a backup, you have continued access to your software if it is unavailable from Adobe.com.
It is users that have inconvenienced themselves if they cannot restore from current backup, effectively shooting oneself in the foot!
What paid software do you have that is 10 years old and still supported by the manufacturer by hosting old versions on their servers?
What financial figure did you put as ‘negligible cost” to keeping old files on servers and maintaining such including staff training for the inevitable trouble shooting investigation including licence registrations?