Not the person you asked, but I believe he is referring to the lack of arbitrary modulation mapping in Ableton, where modulation is typically one parameter on a synthesizer, effect or other device being changed over time by an external source such as a Low Frequency Oscillator (LFO).

Many Ableton devices have features such as this on specific parameters like filter frequency but, without Max for Live, you can't map custom modulations from arbitrary sources.

Here is an example on one such Max for Live device, pitched as a 'general purpose' LFO: https://www.ableton.com/en/blog/lfo-20-free-max-live-device-...