From a weight lifting standpoint, I completely agree with this. I have been off-and-on with hitting the gym throughout my life. I might hit it hard for 6 to 15 months and then barely use it for a year or so. So when I do get back into it, I am smart enough to start off slowly. Doing pure core work is a waste of the time that I have available. Instead I do these compound exercises as mentioned above. And if there is anything that can be done standing instead of sitting, do it. Example: do dumb bell shoulder presses standing up. You might have to lower the weight compared to what you could press while sitting with back supported but that is actually the point -- you are now working more muscles.

Also, concentrate on form. Don't worry what anyone else in the gym has on their barbell. Once you have the form right, you will likely see a quick jump in the weights you can use.

I also have been doing more work with kettlebells (or similar movements with dumbbells). And I do series of push-ups using things like bosu balls or stability balls that force you to use your core a lot more.