User blog comment:JmLyan/Caela, the Voice of Heaven/@comment-24420226-20160212195907/@comment-7709681-20160213045355

Shyvana is an on-hit (pretty much) juggernaut. Her W's AoE is there to have AoE DPS but is not her main focus (is the bonus on-hit damage and the MS Boost), nor is her R to deal damage, so being marginal is acceptable.

All her basic abilities are focused in enhancing basic attacks, and they do so extremely well, she requires little bonus AD to work, but the scaling is there to make use of the bonus statistic to not be wasted, and to not have high initial damage from both base damage and scaling.

Eventually AS and bonus on-hit damage is what she builds offensively, but just because her scales are low doesn't make them useless, a single point of damage could make the difference, as for high MR it can be solved by her with Wit's End and magic pen. from runes and masteries.

As for ADCs dealing magic damage: Ezreal, Kog'Maw and Corki differ from your opinion.

As for this concept, it is true that the same solution for Shyvanna and the aforementioned ADCs can't be applied to her, as I commented.

Here is not a matter of magic damage scaling from AD, but how could the kit be functional and entertaining as an ADC and as a Support, because as a Support results in no scaling due to the lack of optimal itemization as no true AD Support exists, and as an ADC there's both a suboptimal kit besides the Innate passive and E, and a hybridization problem towards counterplay.