I think you misunderstand. Nobody wants to build from scratch (manufacture?) a whole telescope. But a segmented mission assembled from components that are separ

I think you misunderstand. Nobody wants to build from scratch (manufacture?) a whole telescope. But a segmented mission assembled from components that are separately packaged and perhaps separately launched, is much more affordable and less risky than an equivalent mission that somehow unfolds. And,at some point soon, we'll want spacecraft that are larger than can be lifted in one launch anyway. We do this with the iss, lunar gateway, why not large telescopes or interplanetary spacecraft?