Whether the Drake equation is meaningful or not (& it seems logical) there are way too many unknowns in it.
The average rate of star formation
seems like it could be deduced from number of stars versus age of the galaxy/universe but any change from a steady state of growth of the galaxy (eg. collision with another galaxy) would alter the figure radically. Or if it turns out our theories for how galaxies came about get revised...
How many have planets? 15 years ago we knew of precisely one. Now it seems they're everywhere.
How many of those planets can potentially support life? Who knows? Again we have a sample of 8 (used to be 9) to choose from & we're not even sure yet there aren't strange forms of life around our backyard.
How many develop life? Same sample size.
Intelligent life? We have only one planet that we know has life & it definitely went on to develop life with at least a semblance in intelligence.
That could point to ALL planets that have life will develop intelligence or may have nothing to do with how many could.
and so on...
In fact, the Drake equation is rather useless now, due to lack of information to be able to apply numbers anywhere in it, (except for a tentative figure for star formation) and useless in the future, because by the time we can fill in the numbers we will already know the answer.