I think it's fair comment
In the days of the LDH, 2 London based teams would be stopped from using Twickenham.
And you could then argue that they have an unfair advantage come the prem final, or euro final if it was held there that year.
However, I think home advantage is as much to do with an atmosphere that is generated as it is with a familiarity with a given stadium.
Some stadiums will have nuances that will benefit a team familiar with them, but the fact that Leinster get a huge following wherever they're gonna play, but moreso close to him, is where their advantage comes from