alt Hacker NewsThe native AVR libraries are really good. It's not quite as idiomatic as Arduino, but it's really not all that different.
Beginners can learn frameworks more complicated than Arduino and I think they should. Before Arduino, beginners were expected to write plain C or assembly, and the industry got along just fine. There were still countless hackers and weekend tinkerers. They just had to learn more, which is not a bad thing
If by native AVR, you mean avr-libc, it's nothing at all like Arduino.
Instead of analogRead, you need to write your own busy loop watching certain bits in a register (or ISR), you need to twiddle bits in several registers to set up the ADC the way you want it, etc.
Serial.write? Nope, gotta read the docs, twiddle some bits again, and then you actually do get to use printf.
Those two right there are big hurdles to someone new to microcontrollers. In fact, they're a hurdle to me and I've read AVR datasheets for fun.