I have been using DPM kits for over 25 years and haven't noted any major difference in quality. Which kits are you referring to? They have several types. The "Gold" kits like "Poppa Wheelies", "Emery Lane" or "Harlee & Sons", that have loads of metal castings in them; or the smaller building kits containing four walls and a roof such as "Walker Building", "M.T. Arms" or "J. C. Nickels". Or are you referring to the modular walls? I also have some that were offered after they were acquired by Woodland Scenics like "First Bank" and "Stone Bakery" that have (almost) press-fit walls and many extra parts that the standard kits didn't have. Other than the overload of flash on their metal castings in the "Gold" kits, I have no complaints. Nothing as warped as many Walther's kits and never any missing parts like the older IHC kits.
As far as the reviews, is it possible that the ones writing them might be accustomed to the instant gratification (RTR, Amazon, Alexa, etc.) that pervades our society these days?
Wow! I just went to their website and realized that I have over 30 of their kits not counting dozens of their modular wall packs.
Disclaimer: I have not purchased anything new from them except Stone Bakery, First Bank and some modular wall packs since 2015, so things may have changed.
Willie