Many serious traders start with Excel and it's a reasonable beginning. You can track whatever you want, build your own formulas, and customize endlessly. But as your trade volume grows, the manual entry overhead compounds. More importantly, Excel can't enrich your trades with tick-level data, can't calculate order flow, and has no way to simulate TP/SL combinations against your real history. It captures what happened — it can't tell you why.
If you trade fewer than 30 trades a month, have specific custom metrics no tool supports, or need to combine trading data with other business data, Excel's flexibility has real value.