We’ve already established lower taxes is one of the components of fiscal conservativism.
Have we? You have asserted as much, but that doesn't make it true.
Fiscal conservativism is about prudently managing the nation's finances. It's about ensuring that our government has the resources it needs to fund the programs it wants to support. The "lower taxes" portion of fiscal conservativism has been more recently incorporated because some republicans used to argue that "tax cuts pay for themselves with increased economic activity" but that certainly hasn't been born out by the past thirty years of experience. Key to that argument is the implicit assumption that we're not trying to destroy the government, only trying to make sure that it spends in proportion to its income. They supported "lower taxes" because they argued it would lead to increase government revenues, not because they wanted the government to make less money.
For example, the government makes money from a variety of sources besides income taxes. We generate billions from leasing federal lands to oil and gas companies, and these lease royalties are federal income. Do you think fiscal conservatives would suggest that we stop leasing land to oil companies, because the government should have less income?
Taxes are just income too. Not just income tax, but corporate taxes and OASDI taxes and sales taxes and property taxes, they all contribute to government coffers and then government uses those funds to pay for stuff. A prudent financial manager would ensure that we don't pay out more than we make. I see absolutely no reason why a prudent financial manager would suggest lowering your income.
And that's the great lie of fiscal conservativism. It's really just angry rich capitalists who don't want to fund the government programs that have made them into rich capitalists (i.e. roads, courts, power grids, education, etc). They try to couch this "I want to be richer" argument in the language of fiscal conservativism as if there were some moral imperative behind it, instead of personal greed. The current crop of republican politicians have really turned this argument up to 11, by feeding the angry rich capitalists they lower rates they wanted, while simultaneously increasing spending in a way that very clearly highlights the complete disregard for prudent financial management principals that used to underlie their fiscal conservativism rallying cry.