Advantages and drawbacks of opening 1NT with a 5 card Major
Advantages:
- It makes it more difficult for opponents to intervene
- Morfe likely for string hand to play contract thanks to transfers
- Facilitates further biddings & developments
- reduces rebid problems which are frequent after a 1 Heart or 1 or 1 Spade opening
The main drawback is the risk of failing to find the 5-3 Major fit et même 4-4 when the responder does not use the Stayman (less than 8HCP or 4333 distribution)