Yes, you can obviously rebuild engines, transmissions, diffs, etc., change ball joints, shocks and such.
But it's not quite like on an older vehicle.
If I put my TRX on the 2-post lift, for example, chances are good that the shocks have to be recalibrated afterwards. You can't even bleed the brakes in normal fashion anymore.
To me, "working" on a modern car usually means trying to defeat as many of the nannies as possible, then hope that nothing needs to be worked on while I own it. It's just not anywhere near as fun.
Would you want to build a new electrical system to your liking, from scratch, for your '13 Mustang, for example?