..Maybe you are a company that can justify having Quickbooks.. That's above my pay grade. Besides, most service work doesn't involve major material or dollars.. Maybe in your state there is some advantage to doing that. Not here.
Yes, if possible Keep It Simple Stupid (KISS). However, reporting income & expenses is difficult without a transaction ledger, either by hand, spreadsheet, or something like Quickbooks.
One problem with big-dog software is you need an IT department to keep up with forced obsolescence, operating-system upgrades, backup systems, and subscriptions for separate modules and functions excluded from the basic package.
My CSV ledger has used LOTUS 1-2-3 since 1990, on WinXP since 1997, w/ thumb drive backups offline. A ledger prepares me for any CPA, IRS, or audit without bid-dog software platforms, anti-virus systems, hackers, viruses, or security breaches. My iPhone is used for online orders & bank transactions.
In States with income tax, if clients don't purchase material by retail-phone sale, or get the receipt delivered, any truck stock sold for profit after supply expenses, aka (COGS), is properly reported as income and taxed by both Federal & State tax returns.
Have not considered state sales tax exemption certificates, for CA income tax, nor read about any advantages for a minor service businesses.