No they shouldn't play a game if they can't afford to sub to it. All MMO's back in the day (EQ, AC, DAOC, UO) had only monthly subs, and if someone couldn't afford that, they wouldn't be able to play. Now, you didn't say THIS game, you said A game. If that game only has a sub (ESO, FF14) and they can't afford it, they shouldn't play it. If it is F2P or has a F2P option, like this game, then sure, they can play it but they won't get the optimal experience.