For sure, synthetics are an important strategy, especially after hours when traffic is too low for real-transaction volume to be consistent. But if synthetics are all you have – you’re going to be in trouble! Those marketing sites are apparently not being managed. There isn’t much point in monitoring if there is no one to respond to the incident!
Any APM strategy has to allow for those apps/services that are initially unmanaged and could quickly be illuminated with log monitoring or synthetics. For tier-2 and tier-3 apps – this could be all they ever need. But for any app/service of significance you need to quickly follow up with deeper visibility – to whatever that implementation can support. Our first job is to get some visibility, any way we can. Our second job is to start using this information to improve the software service – not simply alert that it has ‘hit the fan’. Otherwise, you end up with a practice that measures “craters” with great precision – but never learns how to avoid the accidents in the first place.