I play on OHS, with -s6borc mode. Thus these are a very frequent appearance in my games (i'd estimate 1/2-1/3 of all games). These are problematic in my opinion for a number of reasons:
1. In the hands of a skilled player, they far exceed others (barring some very rare variants of 1-hit) in how strong they are, both in pushing power and in terms of hero-killing power
2. They are very hard to counter in terms of items: infernals can arguably be somewhat dealt with with battlefury/maelstrom, but it still requires you to have a lot of farm to be able to stand up to the infernals in the first place. Much more than can usually be attained before the rearm player hits lvl 8+ and can start rearming his ulti
3. They completely change how the game is played. Instead of playing against heroes like ordinary, you usually end up futilely trying to clear your base of wards/infernals in one lane while the opponent TP:s to the other and summons 4-5 new rounds there. This ends up being both boring and very frustrating in a game designed to pit custom heroes against each other.
The end result is usually that you will lose any game against these builds unless the rearm player is very bad at dota, or you are already stomping the other team hard enough that you can push raxx at ~15 min. "Ganking" the rearm player doesn't really work in practice because you usually need 2-3 players to kill him, and if you fail you will likely upon up an opportunity for him to take a tower on the other side of the map. If you are successful he will usually be able to buyback due to his superior farm and take a tower nevertheless. Even if you succeed you are unlikely to accomplish much as you quickly need to back off to your base as soon as he respawns. These above scenarios of course assume an almost 5v1 scenario vs the rearm player, which is of course not the case in a real game.
Currently these are locked behind -rc mode, and I would suggest one of the following:
1. Banning the combos entirely
2: Removing other, less powerful combinations from -rc thus making it exclusive for these and allowing the others in -s6bo
3: Allow items to somehow counter MSW/RoC. Someone suggested making diffusal purge having unlimited charges in another thread, which I think is a good idea. For wards I would suggest making mael/mjoll/cleave effects work on them. There would thus be a way around "losing by draft" and allow you to adapt. The rearm builds would still be a threat due to their pushing power, but you would actually be able to stop the pushes somewhat with the right items