Transact-SQL Help - CASE Statement And Group By

I've always been mistified why you can't use a column alias in the group by
clause (i.e. you have to re-iterate the entire expression in the group by
clause after having already done it once in the select statement). I'm
mostly a SQL hobbiest, so it's possible that I am not doing this in the most
efficient manner. Anyone care to comment on this with relation to the
following example (is there a way to acheive this without re-stating the
entire CASE statement again in the Group By clause?):

Select 'Age' =
Case
WHEN(SubmittedOn >= DATEADD(dd, - 30, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 0, GETDATE()))THEN '0-30 Days Old'
WHEN(SubmittedOn >= DATEADD(dd, - 60, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 31, GETDATE())) Then '31-60 Days Old'
WHEN(SubmittedOn >= DATEADD(dd, - 90, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 61, GETDATE())) Then '61-90 Days Old'
WHEN(SubmittedOn <= DATEADD(dd, - 91, GETDATE())) THEN '91+ Days Old'
ELSE cast(SubmittedOn as varchar(22))
end,
max(SubmittedOn), COUNT(SCRID) AS NbrSCRs
From SCRView
WHERE
(StatusSort < 90) AND
CustomerID = 8 and
UserID = 133
group by
Case
WHEN(SubmittedOn >= DATEADD(dd, - 30, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 0, GETDATE()))THEN '0-30 Days Old'
WHEN(SubmittedOn >= DATEADD(dd, - 60, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 31, GETDATE())) Then '31-60 Days Old'
WHEN(SubmittedOn >= DATEADD(dd, - 90, GETDATE())) AND (SubmittedOn <=
DATEADD(dd, - 61, GETDATE())) Then '61-90 Days Old'
WHEN(SubmittedOn <= DATEADD(dd, - 91, GETDATE())) THEN '91+ Days Old'
ELSE cast(SubmittedOn as varchar(22))
end
Order by max(submittedon) desc

Thanks,
Chad