I can’t believe, that I open that can during my lunch break and I won’t dive deeper in another rabbit hole, but I couldn’t resist to ask Chat GPT 
, that’s what he (or is it she, or both?) answered:
Why don’t acoustic guitars have maple fretboards?
ChatGPT
Acoustic guitars typically don’t have maple fretboards for several reasons:
- Tradition and Tone: Rosewood and ebony are traditional choices for fretboard materials in acoustic guitars. They are chosen not only for their aesthetic appeal but also for their tonal properties. These woods are known for producing warm, rich tones that complement the natural resonance of acoustic guitar bodies. Maple, while a popular choice for electric guitar fretboards, tends to produce a brighter, snappier tone that might not be as desired in acoustic guitars.
- Density and Durability: Rosewood and ebony are dense hardwoods that offer durability and stability, which are important factors in the construction of acoustic guitars. Maple, while also a hardwood, may not offer the same level of durability or stability, especially when subjected to the tension of steel strings over time.
- Aesthetics and Tradition: Acoustic guitars often prioritize a traditional and natural aesthetic, and rosewood and ebony fretboards are considered classic choices that complement the look of many acoustic guitar designs. Maple fretboards might not fit as well with the aesthetic expectations of acoustic guitar players and enthusiasts.
I guess, this is a sum up of Mr. Google’s wide range of answers .
To what I read, tone woods generally used for guitar bodys and tops like mahogany, (sitka) sprouce, etc, don’t resonate too well with the maple fretboards on acoustics (obviously no problem on solid body electric guitars as they do often have bodys from mahogany and maple fretboards? And does the fretboard have so much impact on sound?). A second thing I read, is simply some kind of “conceit”, as maple is or has been cheaper than e.g. ebony and therefore maple has been considered as “second” choice
So time to close this hole!!! Thanks for giving me food for thought during lunch break, I almost got bored 
!