In some situations, if you have a lot of the input of a specific industrial good and you have a high enough demand for that good you can start moving to over produce this good and if you get to a certain point every other country in the world that resource will start failing and can destroy an economy. This can be really good against countries such as Romania (Oil<Fuel), Brazil or Netherlands (Rubber < electronics, etc), Any country that produces fabric if you have the majority of the dyes on the market, any country that produces lumber if you have a lot of timber, etc.
This strategy is even more powerful when you are playing MP as generally in MP the overall demand for anyone good is lower as they are produced like crazy all over the world. I speak when experience as a MP game I'm in as Brazil had the industry completely wrecked for 5 years in the 1890s, 300,000 unemployed craftsmen... the crippling subsidies... ugh. 700 industry score down to 500 for 5 years and subsides from 400 to 2000. So while this is hard against the AI if you do MP its very powerful.
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