Pure numbers.
When you tool up to produce , do you go after the market of 1000 possible users or 10,000.
Very few people have the wherewithal to attempt something on this scale and those that do typically expect a return on their investment.
There are options out there , as stated above.
It is getting better.
But MoPar is still third fiddle as far as most aftermarket manufacturers are concerned.
One thing that comes from all those parts being made, there is alot of ways to build a mis-matched Chevy.
Cost, if you look at Chevy's running in the low 10-second range, very few oem parts.
Get to the 9-second zone, you would be hard pressed to find any OEM chevy parts in the engine.
Alot of MOPARS still using the OEM blocks in the 9-second range, both small & big blocks.
The biggest thing that held the MOPARS back for years, was the lack of aftermarket heads.
While it may cost a little more for the MOPAR, most of the parts available by the aftermarket are well thought out componets. Not so with the Chevy stuff.
We as MOPAR fans have alot to be happy with.
Aftermarket; blocks, heads,cranks,rods, with many combinations.
The key here is to build the right combination, as it is with all manufactures.
Next step, find a True MOPAR machine shop! Very few genaral machine shops can do great work on all brands.
Now, I'm a low buck bracket racer & have been quite satisfied with my MOPAR combos.
They have always exceeded my expectations, they run faster & quicker than other brand X engines that have tree times the money invested in them.
I have a Chevy buddy, that has a Nova, He couldn't ran as fast as our Demon with his 327.
So he bought a Jegs 383 stroker, still not as fast. it lasted less than a year before it blew up. I quess my question is, how was that alot cheaper to run a Chevy? Two different engines, three convertors, two different gear sets, He couldn't outrun my .020 360 stock crank, rods, & block. The trickest part of my engine was the out of the box Eldlebrock heads that was on it. Et's, my best was a 11.28, his 11.60.
Now in all fairness, the 360 did break at the first of this race season.
I had a KB piston completely leave town.
This engine lasted 5 race seasons, thats 925 passes without any freashning at all.
At the start of the season, it only had 7% leakage.
it also won 4-Championships & 20K in winnings, just think what I could have done in a Chevy. I guess that I could have marveled at how cheap it was to rebuild the chevy every time it broke.
MOPARS RULE!
ops:
stuff that if (in their "expert opinion") you're not serious enough for them, they'll blow you off. 
