There's the fact that the Catalan government is committed to becoming an EU member upon independence, for one.Self-serving local politicians scapegoating the large political union to which they belong? Token symbolic changes being used to drum up nationalism? Selling the prospect of a future that doesn't fit with reality?
Is there really much difference between the base motives driving the Catalan independence drive and that of Brexit? Unlike say Scotland, if it bids for independence within the EU post-Brexit, Catalonia is simply pitching for no real change beyond warm fuzzy feelings and symbolism driven by a resentful nationalism.