Baha'is have what Baha'u'llah wrote, and that is our guide.
This to me is one of many big differences between Quran and your scripture. You guys emphasize on writing as the guidance while Quran emphasizes on the chosen channels of scripture more then scripture itself. That is more of Quran is emphasizing on the personality of the guides (which most were Prophets) and taking guidance from them in current time, then relying on scripture.
The Quran is reminding of a reality that reminds of God. The reminder is said to be Mohammad (s) and so is the proof as well as it said to be contained in the Quran. The family of reminder means family of the Quran and Mohammadiya light.
The body of the Imam in public has never been a guarantee of guidance. Rather, they were killed one by one. However, the light of the Imam is something that never goes away. God wants people to realize the light of the leadership he bestows his chosen.
Inwardly, that is inside us. The Imam lives inside us and believers are guided through his light.
Moreover, more of Quran emphasizes on miracles as signs then verses of Quran as signs. Quran is a miracle, but the Quran doesn't call the Torah one of the nine manifest signs sent to Pharaoh nor the words of Musa (a) as one of those signs.
Miracles are needed in real time. There is a guide who can perform such things in every time. The Quran was not available to all of humanity when Mohammad (s) was alive, but Quran says that Mohammad (s) was a guide. It means, guidance is not only not just Quran, but takes place without Quran as well. That is believers in other lands who yet to hear the Quran can still be guided by the light of Mohammad (s) and his leadership in the unseen realms. And Imams (a) can teleport anywhere and so Mohammad (s) was able to show miracles to any human by God's permission. However, Quran was not revealed everywhere for sure.
So "for every people is a guide", means the warner Mohammad (s) is such a guide while can only warn disbelievers with such signs, is in fact, a guide to all people and all that is needed be guided is to turn to God often. Ali (a) then is the guide for people after, and so Imam Mahdi (a) is the guide right now.
Also, Bahai writing and Quran both of them, you have to derive from them application to real time. But real time events are not explained explicitly, rather, we have to make analogies with events of our time with events of that time and also tell the differences, so we don't misapply.
Not everyone will be guided in that respect. Quran contains a guidance, but per hadiths, what it guides to is the Imam of time. The Imam of time on the other hand will not only guide you about current events, but reveal hidden secrets of the plan of devils from humans and Jinn, and will assign what a person needs to know and what they can contribute. God's plans are secret, top secret, revealed to Imam Mahdi (a) every Night of Qadr, and Imam Mahdi (a) assigns who what to do.
Joining God's plan and being part of it, is important. Because if you are not part of it, you might think you do something good but are really opposing the plan. Plus, the plan, takes account what everyone must do and what Satan and his forces are planning as well. Being out of the loop would mean we can't contribute significantly in the battle between good and evil.