Soo what you are saying is Madonna had to work much harder to become as popular and famous as she did compared to Lady Gaga who had the benefit of streaming and "branding and ad revenue.". Yet Gaga has been trying to keep herself relevant the last 10 years while Madonna probably sold more singles for Like a Prayer in the opening weekend of Deadpool and Wolverine than the amount of people that even went to see Joker 2 worldwide.
No actually i'm saying the opposite.
Pre 1995 album sales were all there was, I mean you could take your cassette recorder and hold it up to the radio and make a copy of it -background noise, DJ intro and all- but yeah, album sales was pretty much the only way to listen and own the music so of course popular artists sold more albums back then than they do now. Now we measure by streams and earlier we measured by singles sold on itunes, things that weren't even a thing back when Madonna was popular.
So yeah in Madonna's time, if you heard a song you liked playing on the radio, you went out and bought the album. That was your only choice. Of course her album sales are higher than modern artists. Newsflash, the beatles sold more albums than Mozart, could have something to do with there not being albums back when Mozart was making music. But it doesn't change the fact that we like to compare artists from different era's and come up with ways to measure how "culturally relevant" they are.
Also keep in mind, Madonna has 40 years and 14 albums worth of sales, worth of concerts, worth of samples and rereleases in popular media such as you mention "Deadpool and Wolverine", etc. Did you know that she had 14 albums? No, you only remember the first couple. Just like you probably didn't know that Prince released nearly 50 fucking albums, 3 of which after his death. All you know is Purple Rain.
comparing album sales from a 40 year artist who made most of their biggest hits pre 1995 vs a 15 year artist who made most of their sales post 2010 is fucking retarded. It's like comparing youtube followers or total plays, Lady Gaga has 4x as many followers on youtube and about 10k x more plays (many billions) than Madonna does(low millions), but you are comparing apples and oranges. There was no youtube when Madonna was popular, most of her fans are fucking 60+ years old now they prolly don't know how to internet.
A more accurate comparison would be, "at this point in her career, how many popular songs did Madonna have, vs Lady Gaga?" I count 8 hits for madonna over this time period and 9 for Lady Gaga:
Madonna 1983-1999 (16 years)
"Like a Virgin"
"Material Girl"
"Like a Prayer"
"Express Yourself"
"Erotica"
"Secret"
"Take a Bow"
"Ray of Light"
Lady Gaga 2008-2024 (16 years)
"Bad Romance"
"Poker Face"
"Alejandro"
"LoveGame"
"Just Dance"
"Paparazzi"
"Telephone"
"Born This Way"
"The Edge of Glory"
again even this isn't really a great comparison because back in the day when album sales ruled all you really only had 1-2 hits per album with a lot of filler so Madonna's hits are spread out over a lot of albums where Lady Gaga's come mostly from a double album with a ton of hits followed by couple off the follow on albums.
edit: If you want we can also compare "at this point in their career how many shitty films they have starred in" and you'll see that they are basically the same person following the same trajectory. Sorry boomers but Madonna's cultural relevance faded before most of us hit puberty. (Those of us in HS/College when EQ1 launched)