Are heavy scalars natural in minimal supergravity?

It has been recently claimed that very large values of a universal soft mass term m_0 for sfermions and higgs bosons become natural when M_top is close to 175 GeV if tan\beta\approx 10. We show that very large values of m_0 require accidental cancellations not guaranteed by experimental data or theoretical assumptions, and consequently an unnatural fine-tuning of the parameters.