Designing a small collection of different aircraft, each specialised to a particular role, can produce a complementary fleet with capabilities a modern air force needs. But doing so comes with the overhead of producing lots of different aircraft.
Instead, "the spreadsheet" shows that designing one aircraft capable of lots of things comes with the lowest overheads -- but with all the disadvantages of an overcomplicated aircraft and only average performance in each trait.
Designing a small collection of different aircraft, each specialised to a particular role, can produce a complementary fleet with capabilities a modern air force needs. But doing so comes with the overhead of producing lots of different aircraft.
Instead, "the spreadsheet" shows that designing one aircraft capable of lots of things comes with the lowest overheads -- but with all the disadvantages of an overcomplicated aircraft and only average performance in each trait.