No chain purchase coming out of a rented place gives more flexibility as well.
We thought the same as we sold our old place, put everything in storage, had large lump of equity and mortgage ready to go. Even moved in with parents so we could continue to save and have no ties around a rental property.
When we complete later this month, it will have taken 11 months and 3 weeks after selling our old place. We got let down on 3 properties regardless of offering full asking price on all 3, one seller decided after several months of us waiting she simply didn't want to sell after all.
It's cost us £15k+ in not being able to port our mortgage within the window (which I spent ages negotiating an extension from 3 to 6 months), surveys, searches, solicitor fees and storage before we've even started buying our new place. Add into that the hundreds of hours I've spent on the phone to solicitors, estate agents and mortgage providers as well as the time spent viewing properties (we viewed over 80 properties in 8 months before it all started progressing with house no.4).
While you may think you're 'perfect buyers in the perfect position', you're entirely at the mercy of others and I really cannot underestimate what utter time-wasting cunts there are out who think nothing of fucking you over at the drop of a hat knowing there is zero comeback on them.
With that said, good luck to anyone going through a house sale / purchase at the moment