Currently, 15 NBA teams are either out multiple first round picks, prohibited from trading more, or have their picks "encumbered", which means they can't trade them for multiple years.
In the fall of 2017, there was an item on the league's preseason board of governors meeting agenda that called for a vote on a rule that would ban trading pick swaps to teams that already owed future first-round picks to other teams. A vote was eventually taken off the agenda for the rule.
In subsequent years, we have witnessed a surge of superstar trades including multiple first round picks and pick swaps.
Seven teams are totally locked out of the draft-pick market this season at the trade deadline with the Washington Wizards effectively making a provisional eighth.
Because so many teams have a limited ability to trade picks, it could inhibit the market for the next star who wants out.