[jvmboi]

I could easily be wrong and I am very open to learning as what I wrote is just my intuition developed from playing KSP.

The Apollo's "lunar module descent engine" weighs a mere 180 KG vs the approx. 4200 KG of the rest of the craft (dry mass). Just the fuel for the descent is then roughly 8000 KG.

Obviously, landing on the moon is possible but I do think that the inherent requirement to have engine(s) and fuel tanks below the payload makes landing in a vacuum a bit of a challenge.