When I saw that Arthur was born Sculcoates, it seemed odd to me too. However, I can't find another Dawson/Lightowler couple that he could belong to, and in trying to find anything substantial one way or the other, just ended up with a bunch of possibly just circumstantial stuff.
As you say, the findagrave entry for Arthur says he died at Cable Street.
https://www.findagrave.com/memorial/226554533/arthur-dawsonIn the 1911, there is a John William Dawson on Cable Street, with wife Fanny Jones.
When this couple married in 1895, one of their witnesses was a Harry Dawson.
John William Dawson, son of John, in the 1881 census, lived at 6 Hilledge Road.
From the marriage of Harry Dawson to Mary Ann Lightowler in 1906, Harry's address is 4 Hilledge Road. During the war, address was Shelley Street, per his army records up to at least early 1920's In 1939, the family is back on Hilledge St.
I got frustrated and stopped looking. As the OP stated, there are a LOT of Dawsons!
Possibly the Sculcoates birth was a result of a lying-in at relatives, and possibly the children were sent to various homes if measles/TB etc had hit,....or there is some other Dawson/Lightowler couple out there. Only Arthur's birth registration will sort this one out!
Edit:
https://www.findagrave.com/memorial/226915132/joseph-lightowler 4 Hilledge, Mary Ann's father