Rugby is not noted for its academic prowess, although as with most of these type of schools there will be some bright kids there.
That said, all the kids I met at Rugby (and the former pupils I know) were/anre average to below average IMO.
So how would Rugby offering academic scholarships suddenly mean it can “compete with top sets at hot houses”? They are not wholesale changing their pupil cohort, teachers and facilities
it simply means they are trying to boost exam results by attracting a few super smart kids who would do well at any school but who likely had not previously considered Rugby.
So it does not mean Rugby suddenly become an Academic powerhouse and that all the smartest kids will suddenly start preferring it to Westminster, Eton and Eton and Tonbridge.
you also need to consider the culture, reputation and overall prestige. Those other 3 schools (plus some others) are more attractive than Rugby if you are familiar with all schools and highly academic