Before filing a feature request, it may be useful to understand how the upstream operates.
The Phabricator upstream is Phacility, Inc. We maintain total control over the project and roadmap. There is no democratic process, voting, or community-driven decision making. This model is better at some things and worse at others than a more community-focused model would be, but it is the model we operate under.
We have a cohesive vision for the project in the long term, and a general roadmap that extends for years into the future. While the specifics of how we get there are flexible, many major milestones are well-established.
Although we set project direction, the community is also a critical part of Phabricator. We aren't all-knowing, and we rely on feedback to help us identify issues, guide product direction, prioritize changes, and suggest features.
Feature requests are an important part of this, but we ultimately build only features which make sense as part of the long term plan.
Since it's hard to absorb a detailed understanding of that vision, describing a problem is often more effective than requesting a feature. We have the context to develop solutions which fit into our plans, address similar use cases, make sense with the available infrastructure, and work within the boundaries of our product vision. For more details on this, see below.