First off you shouldnt assume all brown people are Muslims. I'm brown and not Muslim, wasn't raised a Muslim, if I cared to trace my ancestry back 200 years there wouldn't be a single Muslim there. I don't think I can relate to any of the discrimination you face. Occasionally I am confused for a Muslim or Pakistani (due to how Pakistanis were much more prevalent than any other minority where I grew up) but people don't call my ethnic group terrorists or child molesters or rag heads or whatever.
As for your two bullet points, I don't think it's possible, or even worthwhile trying to quantify who gets the most discrimination hurled at them. If you ask a Jew, they may cite /r/conspiracy or /r/worldnews as anti-semitic places, if you ask a trans woman she might think that she faces more discrimination than you. One reason you see discrimination against Muslims as being more prevalent is because you are on the receiving end of it, and most likely don't think it's true. You take note of where it happens much more than when someone makes a racist comment about Africans or Vietnamese immigrants.
Reddit is certainly an echo chamber in many places, the defaults are the worst place for this. You are unlikely to get your voice well heard regardless of your opinion because the topics involving the middle east, israel, child sex gangs in the UK, etc. (that all have involvement of Muslim parties) are pretty contentious with lots of comments.
Here's a few things to consider:
People don't really have any sympathy for Islam as a religion the same way they don't have much sympathy for Christianity. It's a religion of over 1 billion followers, in a lot of countries it is the majority religion and has stamped out other religions. Many of the human rights issues in MENA are the result of following the Quran and applying what is in it to state policy. The subjugation of women and sexual minorities, extreme and cruel punishments like stoning and dismemberment, etc. while perhaps not instructed as such in the Quran (I have not read the entire thing) is practiced primarily by Islamic countries with justification taken from the Quran in many cases. It is a human instinct to observe events and look for patterns, and the pattern with Muslim countries is poor human rights records and an inability to adapt to modern conventions. The staunchness in Muhammed's status as the final prophet whose word cannot be altered contributes to this.
In the last two months we've witnessed the Charlie Hebdo shootings and the backlash/reaction to them. There's been a massively increased negative sentiment towards Islam because of that. Reddit isn't pro-Islam any other time but especially after those attacks the anti-Islam sentiment increased.
There is a lot of dislike for Muslim communities in western countries that are seen as making no effort to integrate. Obviously some Muslims have integrated very well, do not expect the same culture from their homelands to be present here etc. but at the same time others have not.