"Modern steel technology" is not what tanks boast as their primary defense these days. Armour technology uses reactive armour on top of steel armour, which can repel conventional explosives.

But shoulder fired anti-tank weapons have moved on from conventional explosives as well -- javelins for example contain 2 warheads -- one to predetonate the reactive armour, and a second charge to penetrate the regular armour.

Its a continual arms race, neither tank nor ATGM can claim dominance, and one hasn't moved beyond the other in a meaninful manner yet.