We are not telling people to develop plugins for perf _instead_ of ftrace. The former doesn't supersedes the latter. They are complementary. ftrace is not deprecated. What is deprecated (in most cases) is the old ftrace plugin system (struct tracer) for new tracing code, altough it's still relevant for older tracers like function, mmiotrace, etc... Instead we recommend to use the ftrace trace event API because it is much more powerful, and it also creates events directly usable by perf.