That's a little hyperbolic. There's a lot of mechanics at play in generating microplastics. Fabrics have microscopically thin strands of plastics. It should be no surprise that rubbing up against thousands of tiny strands every time we move and wash synthetic fabric clothes releases many tiny particles. Plus clothes have to deal with UV degradation making the plastic more brittle.
The plastic components in an RO system should be specced to not leach plasticizers. They should have smooth walls and laminar flow. There shouldn't be much to abrade the plastic surfaces and shed particles. They may not be perfect, but water from an RO system will have orders of magnitude fewer microplastics. So an RO system still "does something about it."
We do need to address the problem, but I wouldn't want people to avoid beneficial remediation just because it has some plastic components.