Doklam and Doklam plateau are two different things, China wanted to own Doklam not just the plateau, the road till Doka La essentially already covers the whole Doklam plateau. When we station troops there, we have de-facto control of Doklam plateau. Strategically, it was the plateau that mattered, the last big piece of flat land there facing Siliguri. Use google 3D, the plateau area is only at the top left quarter of Doklam, the rest are essentially river valleys with no strategic use.
So when Indians entered the Doklam plateau area, their main aim was not road obstruction, it was road destruction of the completed roads in Doklam Plateau. Why else do you need to bring in 2 excavsatros, you could have used only kumbaya troops instead.
Map from Indian analyst. Doklam plateau is from Batang La, Merug La, Senche La to Doka La, looks like a diamond, essentially the whitish area crisscrossed by the roads there. We completed roads from Merug La/Senche La to Doka La, essentially grade 40 roads, then interference from Doka La happened when we tried to extend to Gyomochen. Gyomochen is not a plateau but it was the original trijunction as per 1890 agreement.
Map from Chinese MOFA