Seems very arbitrary. There's a very similar card game in Spain called Truco (and in Italy called Briscola). Truco accepts communication and even bluffing as a core component. There are very standard system for hidden communication, like a wink representating a particular strong card and pursing the lips means another. Because these are so well known, its common to either wait for the right moment to share info, or intentionally share incorrect values to confuse your opponent. At the end of the round, there's an opportunity to bluff and call "BS", increasing the stakes at every hand. Its a very similar game, but accepting implicit communication changes it completely.