It's not the EA's decision whether to accept or reject an offer.
It's up to the vendor.
You don't know the vendor's circumstances and what they will and won't consider.
EAs just talk nonsense and spout cliches. They'd tell you that someone who hasn't had an offer in a year won't consider offers - it's just EA imbecilic sales gibberish - for heaven's sake never take the word of an EA for anything.
I've never had an offer from someone who wasn't on the market yet but I've 'accepted in principle' an offer from someone who hadn't sold yet - on the undestanding that if I got a proceedable alternative offer, I may choose to go ahead with that.
I've made and had accepted 'in principle' an offer before I was on the market.
If everyone waited until they were all under offer before viewing other properties nothing would ever sell or progress.
Only a fool of a vendor would tell you to bugger off just because you haven't sold yet.
An actual vendor rather than an EA would say - Thanks, I can't accept your offer yet, but I appreciate it, in principle the price is acceptable and I will get back in touch with you should I get an alternative offer. Please contact me as soon as you are under offer too and then we can take it further.
There are many vendors who would rather wait for you to sell and then accept your 'offer' of £20k more than the cash buyer who wants to move in in 4 weeks.
The vendor makes the decision not the EA.
It's as simple as that.