Capacitor question

Last 10 days our AC has been struggling to keep up. Had our HVAC company come out and they said it’s operating fine it’s just old and can’t keep up. It’s 17 years so didn’t seem crazy. We have been getting quotes, including from this company (the highest by FAR). It works as long as it’s below 85 basically.

Today, the unit wasn’t working at all so we had them come again and this time they said it was the capacitor and replaced it - it is now cooling well.

Time will tell but I’m curious, could the capacitor have been slowly dying and the reason for our issues over the last 10 days?