It is common to do such things. Remember that you are not the only one who takes on risk; your brokerage is also on the hook if you pile up losses that you can

It is common to do such things. Remember that you are not the only one who takes on risk; your brokerage is also on the hook if you pile up losses that you cannot cover. Brokerages would rather piss off their customers by forcing them to close positions that, according to the brokerage's analysis, are too risky. Last year a bunch of brokerages raised their margin maintenance requirements on various symbols that were deemed risky in some way (low liquidity, wide bid/ask spreads, etc.), which likely worsened the market crash as even more selling pressure was applied.