The biggest problem we're facing in this discussion is semantics.
For me, domination is a Mickey versus Recon Grenadiers that have already fired their panzerfausts. The Mickey is a deadly threat versus a unit that can only try to hide from it.
A Mickey versus Recon Grenadiers is a deadly threat that faces a credible threat, because while the Mickey can one shot the Recon Grenadiers, they have the possibility of doing the same. Not as good a chance unless heavy cover is involved, but something the Mickey's player needs to consider.
I class threats as deadly for units that can one shot fairly easily, credible for those with the ability to damage and possibly one shot a unit, minor if they have minimal chance to damage a unit, and a speed bump if they can do nothing to a unit but be in its way.
When I talk about using units well, I don't mean you have to be a much better player than your opponent to succeed. I mean you have to use your units based on their strengths, while trying to mitigate their weaknesses. A Sturmpionere has a 33% chance to one-shot any medium walker or lighter, up to 55% if they can use a Sustained Attack. If they can keep to cover on their advance, any walker has to destroy them to take away that threat. They also serve to protect their walkers from enemy infantry threats.
Recon Grenadiers are not walker hunters, but they do retain a significant threat to anything up to medium walkers. So long as even one survives, they can fire all of their panzerfausts. They work better against enemy infantry, and enemy infantry is a major threat to walkers, so that's their primary target. Hell Boys cost over twice what Recon Grenadiers cost, with a range of 1 compared to the Recon Grenadier's range of 4 for 8 dice against the Hell Boys (11 dice at range 2). The Axis could afford to lose an entire squad taking out a single Hell Boys squad and come out with an advantage. Recon Grenadiers hunt infantry, and attack walkers only when they need to. They have a 25.9% chance to one shot a medium walker on a normal attack, with a 70.3% chance to cause at least 2 damage. Jump that up to 45.1% to one shot and 91.2% to damage on a Sustained Attack. Those two Recon Grenadier squads bought for less than the cost of a single Hell Boys squad can deal a lot of pain if used to their capabilities. There's a reason the top teams noted from GenCon both fielded Recon Grenadiers. Their odds of a one shot against a walker are not as good as a Mickey with an open terrain shot at them at optimum range, but it is significant, and something that should not be discounted.
I haven't claimed great ranges for any infantry in close terrain. Close terrain can mitigate any range advantages that exist. That applies to the Mickey as much as to the Luther. If you have to closeto range 2 to fire at enemy infantry, that enemy infantry may well have a shot at you with everything they have. Even for normal engagements, if the Mickey closes to range 4 for an attack, enemy infantry can at least move to range 3 and attack if they move again before the Mickey. The Mickey will not always be able to move in to attack at optimum range, and flit away again before retaliation strikes, nor will 16 dice guarantee a kill, even if the infantry is in the open. If the infantry has cover, the odds drop dramatically.
Playing a simple 'kill them all' mission makes something like the Mickey more of a threat for enemy infantry, but if the Mickey has to enter close terrain with cover for scenario pirposes, the infantry start gaining against the Mickey (or any other walker).
Given a choice, people would want to go to their favorite big bang units for competitive play, but scenario point limits means you can only take so much, so the less flashy units have to soldier on with what capabilities they possess. Fortunately, they can, and while not always gaining a one shot kill on enemy units, at least cause enough damage to make life easier for other units to finish the job. You build an army with some awesome units, but can only take so many. You need to field and use simpler units well to win in harsh competitive play, and not just the awesome units.