Excel does not limit the number of worksheets!
For example, you can create 1000 worksheets using the following VBA code:
Sub AddSheets()
Dim n As Integer
For n = 2 To 1000
Sheets.Add(After:=Sheets("Sheet" & n - 1 )).Name = "Sheet" & n
Next n
End Sub
This number probably comes from the limits imposed by other (legacy) software, i.e. Lotus, OpenOffice etc.