I'd agree with "stiffer" (on topic), but perhaps not "stronger." Strong is the ability to withstand dynamic forces without permanent damage. To use seat tube/seatpost as an example, a frame with a shorter seat tube and longer seat post may be stiffer, but in terms of ultimate stress, I think that a frame with longer (and more flexible) seat tube may be able to take more than a less elastic combination like short seat tube + long seat post.

In thinking about failed frames that I see on this forum, it seems to me that more of them are of the medium/shortish ilk than the large frame sizes. Now, since larger and heavier people generally ride larger frames, you'd think that most of the damaged/broken frames we see would be of that type, if they were inherently weaker. Doesn't seem to me that it's the case. I think that it's heavy bike-punishers riding those "stiffer" short frames that kills them.