Deleted member ID issue

If a member delete his/her profile their ID can't be ever used again. So next time if they join again they will be issued a new ID but their previous ID will not be given to any other member. So it is confusing for example website have 100 members 5 of them delete profiles and joined again, so the last number of ID will be 105 against 100 members. If a member keep joining and deleting profile he/she will be wasting a lot of number of IDs. Also With unused IDs the ID search result would be blank.  Correct me if you kept it this way intentionally.

It's intentionally, it's how mysql unique IDs work 

To expand on this - with the original scenario - what if a member joined and uploads a bunch of stuff. then as with the original membership - rejoins at a later date. It would be nice to allow the user to reuse their original account - so maybe adding an "have you been a member before" feature?

The ID is an auto increment value in the Profiles table.  If the record is removed from the table, the ID is removed.  Dolphin does not assign the ID value, that is done by MySQL based on the last record in the table.