If you're ripping off a competitor, sure, the salaries of your engineers roughly translates to the value of the resulting capital asset. But the most valuable work that software engineers do is the stuff that has never been done before. The salaries of your developers and designers and your product managers go first towards figuring out what a valuable capital asset would look like. Only after that can you start investing in the actual asset.
The same is true for all true R&D, which is why historically the government has tried to provide protections for R&D work to incentivize people to not just churn out the safe bet over and over again. Patents fall into this category, but software patents are (rightly) hard to come by. Through 2022, the risk of software development was offset by the ability to expense the costs and avoid a tax bill, and this was good policy if your aim is to encourage innovation.
The capital asset theory could still work if there were some way to appraise the value of the actual asset you created. But absent such a way, this thinking is deeply flawed for all but the most shovelware of jobs.