I am using a different meaning to the terms "scaling" and "scalable". I am usually not really worried about performance or scaling out a solution. I am often thinking about how I can take a certain approach and scale it out to the more complex scenarios.
Dragging a table to the form as an example, doesn't scale. It doesn't scale because when you need to handle logic, you need to go into significant complexity just to get it. NHibernate does scale, because so far it handled everything that I threw at her without increasing the complexity of the solution beyond the complexity of the problem.
I think that this graph should explain it better.
What we see here are the complexities of solutions vs. the complexity of the problem. The unscalable solution complexity increase more and more as the complexity of the problem grows.
The scalable solution's complexity increase as well, but it increase in direct relationship to the problem at hand. If we need to have a problem twice a complex, then the solution will be about twice as complex.
It can't be less than twice as complex, because you can't escape the complexity, but the other solution is nine times as complex, and the difference between the two only grows when the problem gets more complex.
And that is how I evaluate most of the things that I use. Do they scale? Will I be able to handle more complex scenarios without tool-induced pain?
The solution is allowed to be complex because the problem that we are trying to solve is complex. It must not be complex because the tool that I am using need crutches to handle complex scenarios.