And retrospectively, it worked out much better than a protectionist policy. A moderate protectionist approach with a gradual tapering-off would've been ideal, but - as I have already pointed out - that's not politically feasible.
I'm opposing that. Gradual tapering off of protectionism is not a political impossibility, it's a political inevitability. Countries from Great-Britain to the US to European countries all turned from protectionism to free trade as they developed, for several reasons.
First, their companies, once up-to-date technologically, don't fear international competitions that much anymore.
Second, as a country's companies become more competitive, other countries will be less and less tolerant of its protectionist policies, and push for free trade. Just look at Japan in the 1980's, or the pressure on China now.
Finally, and more perversely once a country got rich through protectionists policies, it has an interest in promoting free trade to "kick away the ladder" to development and gain access to other countries markets before they develop. A good example of that is Great Britain's policy of trying to convince German states and France to focus on free trade, selling agricultural products to Engand in exchange for manufactured goods.
Of course, this assume protectionism works. Indeed, Southeast Asia is full of countries that failed to replicate Taiwan's or Korea's success despite heavy protectionism. Studwell key insight is that protectionism alone ain't enough: you have to force firms to compete so they have an incentive to invest and climb up the technological ladder rather than simply profit from their captive markets. The way Japan, Korea and Taiwan all did this was by forcing firms to export. The revenues from their captive home markets gave them the mean, and their government's willingness to close or merge underperforming exporters gave them the incentive.
To take a favorite metaphors of mine, an economy is a lot like a child. Exposing it to competition outright, for example by sending it to polish shoes in the street at 6 will certainly increase it's earning power in the short term, but it'll prevent it from getting an education that would guarantee higher earning in the future. Likewise, free trade can give any economy a short-term boost (As per Ricardo's thery of competitive advantage), but prevent long-term growth by killing any home-grown companies.
Of course, just paying for all your kids expense while never requiring him or her to do anything is a recipe for spoiling him. Likewise, economies can grow fat an lazy on rent-seeking from corporations if they're not incentivized correctly.