Who did suggest to Muslims to utilize the only useless calendar in the world?

Not only, it has got worse. The Qur’an unashamedly calls Muhammad’s god the best liar, while Satan accuses Allah of misleading or deceiving him (Surah 7:16; 15:39). The same Muhammad didn't feel safe from the deception of Allah

Since ancient times, calendars are made in order to take into account the changes of seasons. The only exception has been the Arab calendar. It doesn’t take into account the four seasons, and is thus useless for example for agricultural and naval purposes.

The utilisation of the moon calendar is made compulsory by Allah, through the revelation of Surah 9.36 “ Lo! the number of the months with Allah is twelve months by Allah's ordinance in the day that He created the heavens and the earth. Four of them are sacred: that is the right religion. So wrong not yourselves in them. And wage war on all of the idolaters as they are waging war on all of you. And know that Allah is with those who keep their duty (unto Him)” (Pickthall) 

All ancient calendars add a month in order to recover the month that gets lost because the lunar cycle is slower. The western calendar adds some days to the month in order to take into account the seasons. But of course, because of that it looses the reference to the moon.

The Gregorian calendar (the most used in the world, introduced 1582 by Pope Gregory XIII) “looses” around six hours p.a.., while the Islamic year has only 354 days. Its accuracy is 96.98%. Someone says that Muhammad took 3.02% as commission

IHS