You are correct that a model that deducts capex and then sets the growth rate at 0% will produce incorrect results. But a properly constructed DCF model will not do that. Projecting growth rates, attributable to capex, for technology companies can be challenging, but not always. In other industries it is routine. In a DCF model valuing oil reserves in a reservoir under development the capex for drilling additional wells will be deducted and the growth in the daily production, and resulting revenue, will also be included. With technology companies, the projected growth attributable to major capital projects is often disclosed in considerable detail.