To become proficient and minimize costs, yes. To merely enjoy one aspect of the photographic hobby (viz. experiencing and enjoying fine equipment), Nikon, Canon, and others can coexist in one's collection.
I started with the Nikon F3/T and have appreciated all the Nikon models from the S2, F, F2, to the F4s. They each have their strong points and unique charm.
Before that, my only Canon was an AE-1P. I have since discovered the Canon EF. I think I will enjoy these two above all other FD-mount Canons.
Then there are the 35+ other cameras...