Sometimes exchange want to make there own money in the best way known to them. Sometimes they would not want to reduce liquidity because there are way they can keep traders in fear of loising there own funds. This can also be a reason to lure more investors and traders to there exchange to depositing there coins. Exchanges makes more money from us in case we don't understand how that works.
We need to be very careful on how e trade without stop lose. This can become a big problem to us.