One issue is the availability of materials. Let's look at tents, for instance. the lighter shelter options now on the market, such as the Zpacks Hexamid or a Cuben tarp from Oware, are at the limits of the available materials. Excess "features" have been eliminated and the sizes reduced about as far as is practical. So until lighter fabrics come along, not much room for weight reduction. And the problem is that the fabrics are not developed for backpacking gear. We are just an ancillary market. I can't think of any fabric developed specifically for tents. All the tent fabrics that I am aware of are either variants of fabrics developed for clothing (Goretex, eVent, EPIC, as examples) or sails and hot air balloons and parachutes (silnylon, spinnaker cloth, Cuben). So new materials for the backpacking gear market are dependent on developments for other markets.
Once we push our gear weights down to the limits of the currently available fabrics, we have to wait for someone to develop a new, lighter fabric for some other use which we can then adopt. The UL backpacking gear market alone is apparently not large enough to make developing fabrics specifically for it a rewarding investment.
Some kinds of gear have not hit this point yet - for instance, anyone with a little imagination can see how an inverted canister stove could be made a good bit lighter than anything currently on the market - and we've seen a few ideas in that direction as modifications of existing stoves on the MYOG forum.
Unfortunately, the "Big 3" - sleeping system, pack, tent - (which make up a large part of anyone's base weight) are all getting pretty close to the limits of currently available materials. So big jumps just aren't possible - for now.