What Excel is actually good at
A one-off calculation, a rate comparison, a list you need to sort — a spreadsheet beats software every time. Nobody should build a form to do something Excel does in two minutes. The mistake is not using Excel; it is using it as the permanent record of a business that has outgrown a single file, which happens gradually enough that nobody notices the day it did.
The four places it breaks
Formulas get overwritten by whoever is in a hurry, and nobody knows when. The udhaar sheet and the billing sheet stop agreeing because both are updated by hand. Stock is a column that only changes when somebody remembers. And the whole thing lives in one file on one machine, so two people cannot work at once and a failed disk takes the business with it. Each of those is survivable alone; together they are why shops move.
What a bill produced in Excel does not carry
A proper GST invoice needs a continuous number series, HSN codes, line-wise CGST and SGST or IGST depending on the buyer's state, and your registration details. All of that is possible in a spreadsheet and none of it is enforced, so it drifts — a skipped number, a rate typed wrong, an HSN left blank. Those are the errors that surface during scrutiny rather than at the counter.
Keeping the spreadsheet for what it is good at
Moving off Excel does not mean abandoning it. Everything here exports to Excel on every plan including the free one, so a one-off analysis, a rate comparison or a list your accountant wants in a spreadsheet is still a two-minute job. What changes is that the spreadsheet stops being the record and becomes a tool you point at the record.