#fashernistas are invested in the world of as it is, are driven by trends and the desire to be seen as normal. It is a critiquing the tendency of some people to value things that come from #mainstreaming sources.
The tag #mainstreaming is obviously crap blinded behaver that leads to people being “blinded” by the influence of #mainstreaming culture, ingrained in these people, rather than something they are consciously choosing. They are not open to alternative perspectives.
“It’s a mess to be composted,” a metaphor that the problem is deep and systemic, and requires a significant amount of effort and time to address. Composting involves breaking down organic matter into nutrient-rich soil, which can then be used to grow new plants. In this case, the metaphor implies that the current system of valuing mainstream sources over alternative perspectives needs to be broken down and transformed into something new and more sustainable.