You can build bespoke software without using bespoke software (other than your own to test or dogfood if applicable of course). E.g. if it's basically a webapp

You can build bespoke software without using bespoke software (other than your own to test or dogfood if applicable of course). E.g. if it's basically a webapp, the chances that it's such a snowflake that existing frameworks are inappropriate and you need to roll your own are extremely slim. (On the other hand, you won't think you're making a game and accidentally create Slack that way...)