As 'Administrator' (not system admin) I cannot change parameter in General Configuration

as a user in the 'administrator' group I can get to General Configuration via Administration, I could in theory make some changes, eg to the Site welcome message.

But I cannot save the changes. The Server Base URL is seemingly a 'System Admin' only field, and is greyed out - fine, however, when I try to save changes the validation logic doesn't seem aware of the fact that I can't change it therefore it should not be set/changed. I get red warnings around:

Please enter the Server Base URL

So, on this page at least, I cannot make any changes, which is I think the intention?