I agree with the point about tool fetishization: it could be just another form of "playing house". That said, optimizing these sums of money is also not going to make you successful. If the tools are providing value then use them and don't fret over $0 vs $10 vs $20 a month. The more important thing is keeping cognitive load low by using simple systems and driving mental focus on the right things.
To take an example: I wouldn't bat an eye at paying for Slack for a two-person startup because A) the integrations means I get centralized notifications and search for updates to all the tools I'm using essentially for free with no ops overhead, B) the mobile push notifications and per-channel settings are nicely tunable to ensure I'm on top of things without getting notification fatigue, and C) I'm already on 10 other Slacks, so it's not adding much overhead to my life overall.
To take an example: I wouldn't bat an eye at paying for Slack for a two-person startup because A) the integrations means I get centralized notifications and search for updates to all the tools I'm using essentially for free with no ops overhead, B) the mobile push notifications and per-channel settings are nicely tunable to ensure I'm on top of things without getting notification fatigue, and C) I'm already on 10 other Slacks, so it's not adding much overhead to my life overall.