It is worse than that. It fills up your accounts cloud storage, where your Google docs, sheets, drive files etc are stored.

Once full you are caught in their trap: pay a monthly fee to the mafia or delete your data!

This flow is intentional and they have set up everything to bring you there. The Photo-Backup popup (and arguably the whole photo feature) helps to shovel users more quickly to the end of the monetization funnel.

storing important files with google is risky business anyway. you could lose them for any other stupid reason, and im sure there is nothing you can do but blame yourself for trusting them.