Maybe I missed something in your question, but in every modeling package, even online ones, you have always been able to numerically specify the size, position and orientation of every object in your scene, with a precision of several decimal points. No need to rely on your ‘eye’ at all.
Yes, you can model accurately in these programs but you really have to understand how construction documents are put together. You aren't going to be able to quickly take dimensions from a drawing and convert it into an accurate 3D model with any of the big 3D model packages out there. When I was an architect, I stayed far away from 3DS max, Maya, Blender, etc because modelling in them felt like drawing with crayons. Its the difference between using pencils, rulers, and compass on a drafting board and using paint and brush on a canvas. And that is what's surprisingly lacking in the market, the accurate measured generic 3D modelling program.