The underlying flaw in this analysis is it assumes ratings reflect actual performance in a given game. A long winning streak becomes far more likely if one of the players is part of several matches while tired, drunk, etc. Similarly a players peak performance is going to be higher than their ELO because that ELO includes games played under less ideal conditions.

ELO is presumably more accurate for over the board games at tournaments where players bring their A game than low stakes online games where someone may be less engaged. That’s IMO more worth testing.