I was referring to Domar’s 1944 article. See e.g. bondeconomics.com/2014/11/burden-of-government-debt-part-i-domars.html
Regarding your underlined part: you need to be careful to not confuse dynamics with the steady state. If you start with the Solow model, you would expect catch-up growth, i.e. the observed growth rates would be bigger than the growth rate you would expect along the balanced growth path. Another thing is the difference between the pure discount factor and the growth adjusted discount factor. In a Ramsey-Cass-Koopman model the beta can be bigger than 1 as long as growth adjustment brings the effective discount factor below 1. See e.g. Romer’s or Acemoglu’s graduate textbook.