most constructive tips I've seen in my life
There is a simple logic. Upgraded Grens have to remain stationary to be effective.
Everything that will force them to move, or is good at hitting stationary targets is effective against them.
You throw molotov you force them to move, thus neglecting their dps, or they will burn in flames.
Mortar will wipe stationary targets with easy. With tanks you just keep them away from panzerfaust range and shoot to death. Or just drive over them.
There are plenty counters to Grens and the further game goes the more meaningless they become as game shifts towards heavy hitters.
Sorry but this topic is just arguing for the sake of arguing.
The statement is false as well.
The only one I agree is that LGM Grenadiers are better than vanilla Conscripts but this is obvious and was designed this way. You have many other ways to deal with LMG than Conscripts.