Most lunar calendars have intercalary months (an additional month added every second or third year) in order to keep the lunar calendar in line with the seasons. For people living in an agricultural society, this would be for a practical reason, so that harvest festivals happen at harvest-time and so on. Muhammad decided to forbid intercalary months, so the Muslim year gains a year on the solar calendar about once every 33 years.
I understand why the lunar calendar is different. What I don't understand is why it is noteworthy that a holiday happens to coincide every 33 years.