The British system at Westminster is more flexible. It places a lot of power in the hands of parliament.
As long a the Prime minister has a majority in the house of commons he/or she can pass what ever law he or she likes.
The the British system parliamentary sovereign not the people.
https://en.wikipedia.org/wiki/Parliamentary_sovereignty
No written Constitution to limit power or uphold the peoples rights. No separation of powers. No independent judiciary.
In the British system political parties have strict whips where mp must vote with their party or be expelled from the party.
With the first past the post system and single seat constituencies. many mps have safe seats.
This system can get grid locked if no party or group of parties has a overall majority in the house of commons.
if this happens parliament can call another general election. This does not always fix the problem,
With the first pass the post system of election tends to favour the large political parties.
https://en.wikipedia.org/wiki/First-past-the-post_voting#Effects
Parliaments without overall majorities or coalition are rare.
What you get with the British system is a elected dictatorship.
I am not sure how well such a system would work in a federal system in a country the size of the USA.
Would the state governments also adopt parliamentary government too?