why do you think shifting cultivation though destructive is still practised in many parts of the world?

The need for new fertile land makes it a bait for communities that practice shifting cultivation to continue. Farming on the same soil for consecutuve number of years make sthe soil exploited of nutrients, therefore, since, this communities do not have mechanisms to restore fertility, or simply cannot afford, then they move to new fertile unexploited land.

Explanation:

Being a communal practice, shifting cultivation is part of the culture of groups that practice it, it is therefore inevitable for them to leave this practice that defines them.

Communal or tribal ownership of land also leads to the continued shifting cultivation since individuals have got no land of their own to maintain, and therefore, move from piece to piece over a period of time for bwtter fertile land.