Even the NTs are often combined with an A-tier for Ams. On the other hand, a few places run lower-tier tournaments for Ams and Pros on different weekends.
The difficulties in running pro-only tournaments, other than at the very top, include
---Lack of significant outside money. This means basic expenses must be paid from entry fees, lowering the payouts, which makes it harder to attract pros.
---Much less merchandise involved in payouts or sales, so less wholesale/retail margin, so little chance to make money for the TD or local club.
---Small number of Pros, except for the highest-level events. If local events draw 20-30 pros, no one will want to run a separate tournament just for them.
---At the local and regional levels, many events attract pros & ams together. They're friends and traveling companions, even if they play in different divisions.
The difficulties in running pro-only tournaments, other than at the very top, include
---Lack of significant outside money. This means basic expenses must be paid from entry fees, lowering the payouts, which makes it harder to attract pros.
---Much less merchandise involved in payouts or sales, so less wholesale/retail margin, so little chance to make money for the TD or local club.
---Small number of Pros, except for the highest-level events. If local events draw 20-30 pros, no one will want to run a separate tournament just for them.
---At the local and regional levels, many events attract pros & ams together. They're friends and traveling companions, even if they play in different divisions.