Who cares if it's "appropriate" or not? It's your money and your planned usage of the computers.
I happen to have two MBPs and a 12" MacBook. So there!
Do I care what anyone else thinks? No. I use all three for various purposes and they suit my needs very well. The 15" 2018 MBP (i9, 32 GB RAM, 1 TB SSD, Vega 20) is my current primary computer, the one which does all the heavy lifting. She replaced a 15" 2015 MBP which is stlll very much loved and still very much used in this household, often while the new machine is engaged in something time-consuming such as copying data from one external drive to another or doing a software update, etc. The 2017 12" MacBook is one of my two traveling companions, the other being an iPad Mini 5. I also use the 12" out on the deck sometimes in nice weather when my 12.9" iPad Pro is on the charger. Sure I could survive with, say, just two computers, but I am fortunate in that I am able to hang on to the older ones while enjoying and utilizing my newest one. Each one serves a purpose in my life.
A lot of people use a desktop, such as a Mac mini or an iMac, but I didn't want to go that route. I've been there, done that, over the years with earlier iMacs and Mac minis, and am aware of the pros and cons of each system. I really appreciate the portability of my MBPs and my MB, and the flexibility of being able to add an external monitor at any time if I decide I need more screen real estate than the 15" MBP provides.
All of us have our own ways of doing things and our own priorities and needs, including choosing and finding what works best, gets the job done.....that's what's important, not what someone else might think is "appropriate" or not "appropriate."
