Or six stops to Custom House and Crossrail...
Few in Thamesmead will do that. The DLR trundle to Custom House would take 20 minutes before changing to a packed Crossrail train. They'll go one stop on the DLR to Abbey Wood then Crossrail with a hope of a seat. Would be quicker too.
However, DLR to Thamesmead then Abbey Wood is a far worse option than London Overground extended over from Barking Riverside. The LO to Barking offers a very large range of transport options - 2 tube lines, LO to NW and N London, c2c to East London and out to various places in Essex. DLR offers very little - Beckton (nothing there or any connections) and then nowt until Custom House & Canning Town, but connecting with those just duplicates existing cross river connections at Woolwich Arsenal & Crossrail from Abbey Wood.
The far greater options LO provides would offer massive regional benefits for outer SE and east London connections, along with better Kent and Essex links, thus people wouldn't have to travel all the way into London. DLR offers no time advantages on what's already there so wouldn't.
The hitch is 4 tph. But could a higher tph service run from Abbey Wood to Beckton alone, with the existing 4tph GOBLIN remaining on its current route, electrified and faster with longer trains? I don't know Beckton too well, but could it be possible for another line/platform to be built specifically for a shuttle from Abbey Wood to Beckton, calling at Thamesmead, Barking Riverside (two stops could be possible at either end of development zone) then terminating at Barking?
Finally, strategic plans see massive housing numbers planned in Thamesmead & Barking Riverside alone, let alone the wider region. A crossing will greatly speed them up helping London's massive housing problem. Thamesmead alone could see 30k extra people but without a decent station IN Thamesmead then forget it.