Was obviously talking about on chain (which greatly affects lightning being usable as we always see when blocks get full onchain). Layers don't carry over the same fundamental properties that make on chain great. You always sacrifice some form of sovereignty like self-custody or permissionless txs so far.

You say that, but still havent explained why. 
Why couldn't Bitcoin even increase it conservatively based off whatever metric was it's bottleneck (just behind bandwidth for example?)

If that is your worry, why hasn't Bitcoin adopted MimbleWimble? MW is even more scalable on chain than even Bitcoin itself. Litecoin already did all the work. 

 Bam!