You can not eliminate the middle man in businesses, especially in this digital age, be it fiat or cryptocurrencies, because they have come to stay. Big exchanges like Binance, are cashing in on being the middle man in businesses, an unavoidable indirect business associates, in your face, waiting for you to go through them.
Unfortunately being a third-party company in a decentralized technology has become a very lucrative business, Satoshi envisioned an environment without the middleman man but the lack of trust between the two parties gives power to the middleman, the third-party system has been with us since time immemorial and unfortunately, it integrates in a decentralized exchange because of the lack of trust.
Honestly, I have more numbers of trades using a middleman than using a peer-to-peer I'm sure all of us here third parties will always be with us, we are so used to it, It applies in many industries it applies in Cryptocurrency.
Reason why we are using the third party application or platform because of it's convenience you can now easily sell or buy the coin you want through using other coin or using your fiat currency unlike going into different site with different service they are now adopting the use of third party applications to make sure their users easily use their platform. Also new comers surely will embrace this too because of recommendations of experienced people and being known with their service. Or else you want to use the old school.transaction where you really meet people to exchange your coins which is more.hassle and risky because you don't know the person you are dealing with at all.