Originally posted by madison_wi_gal OK, so I guess my mistake here was not actually knowing that dSLR = mirror and prism. (the "R" is the key here). My bad. Now I know.
Sorry!
No harm done.
This subject often generates heated debates in which we're told that DSLRs will/should/did die and such; but we're much more level-headed than a certain forum's Open Talk section
photoptimist gave you a good answer. Note that I also consider the mirrorless design closer to optimal from a theoretical point of view, but I just cannot work with EVFs (as in: I get tired quickly, and I can even get powerful headaches). Good quality optical reflex viewfinders are much, much kinder to my eyes. So when you hear about "hate" it might not be the literal meaning.
The SLR design appeared and evolved out of necessity, and it's still necessary for many of us.
A suggestion: try borrowing or otherwise getting both a good DSLR, and a mirrorless with a good EVF - use them a bit, side by side if possible, and in various situations. Some practical experience can tell you more than the SLR diagram from some internet site (though knowing what's inside helps, too).
Have fun!