There are some worthwhile points in there - hiring too many people too early is always a risk and underprepared telesales people can harm your brand - but also quite a few suspiciously specific figures and claims (I particularly like the "more than 34% of the leads you purchase may be unusable" claim, but the assumption the enterprise salesperson isn't doing anything useful to generate business over the "6-18 months to ramp up" is probably the most dubious one).
The validity of most of the claims very much depends on the product, value proposition and industry: there are an awful lot of industries where finding apparently suitable contacts is the easy part, plenty of salespeople whose strength is the network and knowledge that allows them to identify the right prospects at the right time - whether they spend more than 20% of their time doing that or not - and plenty of startups where knowing who your potential customers are is the very last function that should be outsourced.
If you're not a native English speaker, like myself, knowing that "SDR" means "Sales Development Representative" actually turns this into quite the interesting read.
The validity of most of the claims very much depends on the product, value proposition and industry: there are an awful lot of industries where finding apparently suitable contacts is the easy part, plenty of salespeople whose strength is the network and knowledge that allows them to identify the right prospects at the right time - whether they spend more than 20% of their time doing that or not - and plenty of startups where knowing who your potential customers are is the very last function that should be outsourced.