Thats a bit of an exaggeration.
When the Oilers started their rebuild back in ~2009ish (arguably it started in 2007 when they drafted 6th OA), did they have a Rielly calibre young dman on the blueline? No. In fact in 2015, they STILL dont. Theyre hoping Nurse can fill that role.
When the Oilers started, did they have Nylander/Kadri/Bernier calibre young forwards/goaltenders to help through a rebuild? They had Gagner and Dubnyk as somewhat comparable, but thats about it, both of whom are considered worse than Kadri/Bernier, let alone Nylander.
Did the Oilers have the trade returns of Kessel, JVR, Phaneuf, Bozak, etc calibre players? They sold off Smyth, but didnt sell off any other major pieces that I can think of. Leafs should be getting a bigtime boost there.
The Oilers have also been completely incompetent at drafting/developing NHL talent outside of the 1st round. Hunter should help the Leafs in that regard, a team that while not great at drafting, was still producing non-1st round talent like Kulemin, Komarov, Stralman, Reimer, Stalberg, Gunnarsson, Hayes, etc. And have guys coming up the system right now that should have NHL careers (even if just as secondary players).
If the Leafs go full rebuild, theyll be adding a crap ton of young assets pretty quickly by selling off their core. The core are in their primes, so its not a dwindling core in their 30s with declining value. Caphits are an issue, but there are ways around that via retaining salary and/or taking back cap dumps. And they already have a number of interesting pieces worth keeping and building around longterm.