Plenty of directors under PAYE were also excluded. Some were excluded because they didn't have a payroll in the "magic" month of February 2020.
Many paid themselves yearly to avoid the hassle of weekly/monthly filings to HMRC (perfectly allowed by the HMRC/Payroll laws, but not respected by the furlough rules). Some with "lumpy" irregular incomes paid themselves only in months when they had income to pay, and didn't pay in other months, again being excluded if they didn't pay themselves in Feb 2020. All this despite often years of "evidence" to prove that they were paid under PAYE, but just not on a weekly/monthly basis, but HMRC and The Treasury wouldn't listen to reason and wouldn't change the qualifying rules nor make any waivers/concessions.
Others couldn't meet the requirements not to work, to be eligible for furlough, i.e. where they had ongoing obligations to clients etc. and couldn't "shut down" properly which was what was required at the start of the furlough claims. So even if they were down to say 5% or 10% of working, they were ineligible because they were working. It took a few months before the rules were changed to allow for "partial" working and to claim furlough for the time they couldn't work - and of course, the furlough claims for earlier months couldn't be backdated!
It's fine looking back with hindsight and blaming directors for taking dividends and therefore not receiving full furlough, but furlough wasn't even in the UK tax system before covid, no one could have known that we'd ever even have such a system in the UK, so there certainly weren't people paying themselves fully under PAYE "just in case" of a pandemic and it's silly to think there would be. Employers can't even claim SSP anymore! And no, there will be very few directors who've now decided to pay more under PAYE "just in case" there's another pandemic so they'll be eligible for furlough!
It's such a shame that successive governments encouraged the "low salary, high dividend" method of working. They did that, especially Brown, by encouraging small businesses to be limited companies. Changing tax rules on dividends to make paying dividends more attractive from a tax point of view (now reversed), and hiking both employee and employer NIC to make paying wages far more expensive, especially for one man companies who have to pay BOTH employee and employer NIC. Make no mistake, government policies over the past 25 years caused the "low wage, high dividend" remuneration structure because they made it too expensive to go through the "high wage" alternative due to NIC hikes.