Free trade, as a rule, means that the people who can make the best goods for the lowest prices get the customers. This isn't a problem when there is only one country, in fact it's a good thing since it means that in total the country will make more profit and thus more tax money. However, in a globalised system like we have now there is a very real risk of a whole country losing out to foreign competition (as the UK's companies seem to have all done recently) and so in my view some protectionist measures are needed.
The problem there is the whole comparative advantage thing, which is the world's least intuitive important economic concept, near as I can tell. It's not actually technically possible for a country to be "uncompetitive in everything" vis a vis another.
Even if one country (A) has absolute advantage in everything (makes everything better and cheaper and with less opportunity costs), it's still more efficient for the universally disadvantaged country (B) to produce whatever it does best and sell that. And it's better for country A to forgo making that product and import it instead while making something else - even if A got absolute advantage in everything, it still has relative opportunity costs between products. There's
something it makes more efficiently than something else, and so it should focus on that instead. What this means is it's impossible to actually be "uncompetitive in everything", as unintuitive as that sounds.
There are of course other problems. A bigger problem is, I guess, only being competitive in industries which aren't real conducive to development and becoming richer. Agriculture and mining seems to not enrich many countries which are actually quite efficient at it.
Then there's structural problems - a
country may be efficient in something, but that says nothing about the distribution of power or income in that country. A lot of decolonised countries are inegalitarian monocultures because colonial policies deliberately created that situation, and then the local elites just inherited that land and industrial situation.
Then there's the oil curse which is related to this, but the result of the discovery of a resource as opposed to a colonial legacy. The risk there is that one really efficient and productive sector makes all the others
less efficient and productive.
Of course, protectionist measures can also be used to
build comparative advantage in a particular sector.