On the contrary...
I believe for a beginner to fully blossom as an all around guitar player with appreciation for the instrument, and appreciation for the music... they should first start on an entry level instrument. You are correct in making the assumption that a beginner guitarist will either take to the instrument or tire of it. However, most cases... in my personal experience... someone who starts playing and gets bored with it will most likely come back to it from time to time and grow tired once again... In most cases they never sell the guitar... They just don't have either the time or the patience to sit and practice... They take more of a "I'll do it tomorrow" or "One of these days I'm gonna..." approach to learning. If they go out and buy a more expensive guitar... they're out that amount of money because if they're too lazy to learn... they're probably too lazy to put it on ebay or take it to a pawn shop... And in most cases... used guitars... even mid range guitars don't have good resale values. I recommend any beginner start from scratch... The best thing my parents did for me was buy me the cheapest guitar on earth... at the time I didn't know the difference between a cheap imitation strat and an American Fender STRATOCASTER... I played that guitar until the frets were worn to the fretboard... and this is what I learned...
1. Entry level guitars are made poorly... making them harder to play... The action on my first guitar was so bad that my hands got stronger... and I learned how to bend stiff strings to pitch. Also, it didn't stay in tune very long and thats where I learned how to do my own set-ups, intonation, string changes, as well as basic wiring along with some other things...
2. Entry level guitars aren't made to be resold... I still have mine and it's such a sentimental piece of my collection. When I forget what it's like to no play a nice guitar... or I want to be reminded of where I came from... I plug her in and it doesn't take me long to realize how much that guitar taught me.
3. The appreciation factor... Growing up playing a crappy strat... I was never spoiled by a nice guitar... I knew what a bad guitar felt like... and as soon as I got my first American strat I knew what a good guitar should feel like... as soon as I started playing it I immediately felt like a better guitar player... I could play faster, I could bend easier, I could make chords easier... Everything was so much easier... since I had been playing on a cheap guitar with terrible action...
Those are my reasons why my kids will start out with a cheap guitar... It's not JUST about playing the guitar... It's also about learning that you have to start at the bottom... you have to work your way up. It's about making the best of what you got... and it's about the journey. When I look back that first guitar taught me quite a bit about other things besides just how to play the guitar.