The reason the EF even needs to exist in the first place is because while the Ethereum protocol has a built in mechanism to fund security through issuance/fees, there isn't a similar mechanism to fund R&D and other public goods. @vitalik.eth explains this situation well in his post "Moving Beyond Coin Voting Governance"

At the time of the article, Vitalik said that daily mining issuance rewards from Ethereum amounted to about 13,500 ETH, or around $40m per day. That's $40m for security every single day, compared to $100m budget per year from the EF and that doesn't entirely go to R&D. I'm biased but this ratio feels significantly off to me

https://vitalik.eth.limo/general/2021/08/16/voting3.html