Copy/Paste. Massive File. Workflow. (Am I doing this wrong??)

Apparently, you can't copy and paste objects into a new file. 

As a result, I've been forced to create this massive long row of our product sets in one single file.

As a result, the file has become massive, slow to open and unwieldy to work with. 

 

Is this the only possible workflow?

I'm using this to create product set images .. is there a better way to handle it, or is this what I'm stuck with?

 

(Note, I've seen some ads for some kind of new 3D software from Adobe that's a paid upgrade option ... is Dimension – that comes with my subscription – being left in the dust? That is to say, if the answers to my copy/paste problem are "upgrade," that is just dumb.)

By @matt.steinruck

its sort of true but you can export objects out to your library or physically to your hard drive in order to reuse them and that is a much better option than the big long line of models you show in the image

yes Adobe has replaced Dimension with Stager which is very much just Dimension with with extra materials for more $